Football is a game of physics; for every action there is an equal, opposite, and generally violent reaction. Lead a receiver over the middle anywhere near Kam Chancellor, and your best pass catcher is liable to be obliterated. Leave J.J. Watt alone on a below average offensive lineman, and your quarterback will likely hit the ground within three seconds. Not putting two defenders on Calvin Johnson at all times is virtually guaranteeing a few embarrassingly long bombs being completed behind your defense. In an age where football is just as much of an arms race as it is a spectator sport, teams have found creative ways to outfit themselves with new and exciting weapons to help put physics back on their side.

Wes Welker and Tom Brady unleashed the fury of the modern slot receiver on the league in 2007, and in the years since the position has evolved into an entirely new monster. Offensive coordinators are now looking for "slot weapons" with just as much earnest as they are for traditionally dominant outside receivers. Tavon Austin and Brandin Cooks would have never sniffed the first round before wideouts like Welker and Lance Moore started lighting up nickel cornerbacks every Sunday, and yet in today's NFL, both of those prospects are seen as big time offensive chess pieces. With the emergence of those potentially game-breaking threats, a new kind of defender has evolved as well – the slot cornerback.

A good slot corner is a completely different species than his traditional counterparts. Smaller, more fluid, and just as infuriatingly quick as modern slot receivers, a good inside corner is a defensive coordinator’s only real answer for today’s offensive trends. Whether it is having the foot quickness and technical discipline to undercut an out-breaking route on third and five or the flat out speed to trail 5’10" track stars forty yards down the field, a slot corner has to be one of the most adaptable defenders on the team. Suffice to say that it is a position that is exceedingly difficult to fill. Few defenders can handle the role without becoming a liability, and even fewer are above replacement level.

As it stands now, three names rise to the top when debating who is the best slot corner in the league – Chris Harris, Brandon Boykin, and Tyrann Mathieu. Interestingly enough, all three of them are still on their rookie contracts. New age slot receivers have been tearing the league apart for the better part of a decade, and just now is football finally seeing a generation of defenders enter the league that can slow them down. Teams do not even know how to value good slot corners yet because they simply did not exist – nor were they considered a crucial position – until a few years ago. Now, most front offices in the league are doing everything they can to get their hands on one. In short, all three of these men are about to be showered in money never before thought possible for a traditionally part-time player.

Back to the question at hand – who is the best slot corner in the league? Stats, rankings, and team successes all point in completely different directions when trying to give the answer. For the purposes of this article, however, I will make my judgments based solely on game tape. After charting hundreds of snaps and taking just shy of 15,000 words worth of notes, here is how the best of the best fared against one another.

#3 – Chris Harris, CB, Denver Broncos

Richard Sherman is the poster boy of the 2011 NFL Draft as a fifth round pick turned superstar, but it is the undrafted Harris who might have developed into the best defensive back of the entire class. Versatile, tenacious, and almost physical to a fault, Harris is everything a team could want in a cornerback and more. After receiving a camp invite and fighting his way on to the roster, Harris went on to have a fantastic rookie season, earning Broncos Defensive Player of the Year honors. Almost three seasons later, Harris has cemented himself among the top corners in the game.

What stands out the most about Harris is how he was used. Denver lined him up inside, outside, and everywhere in between in both man and zone looks. Whether he was seven yards off the line of scrimmage or three yards away from a tight receiver stack, Harris was asked to master a multitude of different techniques to blanket opposing receivers. Regardless of alignment or assignment, however, one trait consistently showed up in Harris’ tape – physicality. At times it almost looked like Harris could not help himself when receivers got within an arm’s length of his body. Even when dropping into shallow zones, if a receiver came anywhere near Harris, one could be sure he would attempt to slow them down (Ex. 1, Ex. 2, Ex. 3).

Harris’ propensity for jabs and jams would be considered a positive for most bigger boundary corners, but his relatively small frame often turned his physical nature on its head. Not only did Harris lead the Broncos secondary in penalties in 2013, but his effectiveness at jamming receivers was mediocre at best. Victor Cruz and Rueben Randle were able to torch Harris repeatedly in the 2013 "Manning Bowl" simply by running through Harris’ attempts to jam them in the middle of their release (Ex. 1, Ex. 2, Ex. 3).





As soon as Harris stops trying to be something he is not and instead focuses on playing to his strengths, there is no telling just how good he could be. Harris excels when he allows his quick feet, fluid hips, and excellent start-stop ability to do all the work for him. I remember one snap in particular against Dallas in week five when he mirrored an inside release from five yards off the line of scrimmage, recognized a whip back to the outside, planted, and flipped his hips in sync with the receiver all while keeping his eyes on Tony Romo. If he were targeted, that kind of hip fluidity and eye discipline would have likely resulted in something disastrous for the Cowboys.





A perfect microcosm of Chris Harris presented itself in the aforementioned Manning Bowl against the always explosive Victor Cruz. Even when botching a jam against one of the most dangerous receivers on the planet, Harris was still able to use his physical gifts and some nifty hand work to keep his man in check.





Contrary to popular belief, a corner’s hands can be just as important as his feet when trying to cover some of the league’s best receivers. Take this snap in trail position against Dallas’ Dez Bryant as an example. Harris might seem like he is reaching out to Bryant in desperation, but in actuality he is keeping his hand on Bryant’s back to feel the route develop.





As far as deceiving senses go, sight is the biggest con artist of them all. A good route runner can make his steps look like anything he wants them to while the defender’s brain takes half a second to process what it is seeing. Actually feeling the direction and inertia of a human body through touch can tell the brain everything it needs to know in an instant. When contact is established, two bodies can essentially become one. If Bryant were to run a curl or comeback route right here, for instance, Harris would immediately feel Bryant throttle down and he could decelerate himself on instinct alone. Not only does Harris use that contact to feel for a change in the route, but he can convert that hand on Bryant’s back into a pseudo-emergency brake as he uses Bryant’s body to slow his own momentum.

If there is one thing that young corners struggle with in their first few years in the league, it is double moves. Good route runners are few and far between in the college ranks, but even average NFL teams are full of pass catchers that can make a defender’s head spin. Harris’ excellent hand usage has helped him make the transition that drowns less polished corners on a yearly basis. Study the following snap against Jason Witten as an example.

Denver is showing a single high safety look that hints at either Cover-1 or Cover-3 on the back end (red arrows and boxes), but in actuality they will be rolling into a Cover-2 shell as soon as the ball is snapped (blue arrows and boxes).

The Cowboys call a vertical route concept meant to exploit three deep zones by having both outside corners run "go routes" down each sideline. Chris Harris is in the slot in a "catch technique" against Jason Witten. Dez Bryant is towards the top of the screen running a go route on the far sideline. The core concept around this play call is getting the ball to Witten after stretching the free safety as thin as possible. With Bryant on the opposite side of the field from Witten, Dallas hopes to see the deep safety cheat in Bryant’s direction while leaving Witten in a one-on-one situation with Harris down the seam. At the same time, Witten is tasked with selling an "out and up" against Harris. If Harris bites on the initial break to the outside and the free safety cheats towards Bryant as expected, Witten should be wide open fifteen yards down field with nothing more than a cornerback standing between his huge frame and the end zone. Against a standard Cover 3 defense, there is not a more perfect play call than this.

Except Denver is not actually running a Cover 3, and Chris Harris is way too disciplined to fall for a routine out and up.

Denver rolls into their Cover-2 shell once the ball is snapped. Meanwhile, Jason Witten presses slightly inside on his release in an attempt to set up his first break towards the sideline. Harris responds by taking a single step inside and flashing his hands up to get inside of Witten’s chest.





Harris’ great hand usage allows him to not only mirror Witten’s first break to the outside, but also feel the second break back down field. Discipline against the double move was not the worst of the Cowboys’ problems, however, as the free safety was no longer in the position that he showed pre-snap. Tony Romo’s first – and best – read on this play is now completely ruined. If Witten had beaten Harris with the second break, Romo might have been able to fit a pass into the hole underneath the safety, but the young Bronco’s blanket coverage discouraged any pass being thrown his way.





Tony Romo’s wizardry in the pocket eventually lead to a sizable Witten reception anyway, but none of the blame can really be attributed to Harris. He did his job – the pass rush did not.

Hands are not just for keeping one’s self from getting fooled by a savvy route. More often than not, good hand usage is the difference between recovery after being beaten and giving up a huge gain. The league’s best corners have a habit of, when mirroring a release in a certain direction, always keeping their "opposite arm" open like a hook while they settle into trail position on the receiver’s hip. Once in trail position, that arm rests on the receiver’s back to feel for changes in the route. If they overcommit to a fake release and the receiver breaks in the opposite direction before the corner get into trail position, that hook is intended to catch the receiver in the chest where the corner can grab on and slingshot himself back into position. It takes a remarkable level of coordination and a fair bit of strength to pull off, but mastering the slingshot technique is a must for every professional corner.





One of the more dangerous route running techniques that a good corner must learn to combat with his hands is the shoulder ride. I touched on the shoulder ride a while back in my piece on Andre Johnson’s route running proficiency rubbing off on DeAndre Hopkins. For those that have not read that article and want a quick primer on what a shoulder ride actually is, watch the video below.

As with all positions in football, the only way to beat physicality is with more physicality. For instance, this second quarter red zone pass deflection against Mr. Cruz was primarily a product of Chris Harris not allowing himself to be outmuscled in the end zone.





From the end zone angle, we can see the oft-overlooked hand usage that allows Harris to keep the Giants out of the end zone. Take note of Cruz’s shoulder ride right before his break inside and across the back of the end zone. Harris gets his hand in good position on Cruz’s back to feel for the break while keeping an eye on Eli Manning.





Cruz pivots his hips and gives Harris a quick shove to the chest while starting his break to the inside. Harris holds his grip on Cruz’s torso while maintaining eye contact with Manning.





Despite Cruz’s best effort to separate with a stiff arm, Harris manages to drag himself back into position during the break. Once settled on Cruz’s hip, all that is left to do is track the ball and knock it away.









Take a look at the play in full speed from the end zone angle. It really does not get any better than this.





As far as undrafted free agents go, Chris Harris is among the very best finds in the last few years. Tough, versatile, and hungry for a lucrative new contract after partially tearing his ACL six months ago, Harris is one of the big names to watch in 2014. If his recovery from the knee injury hampers his play at all this season, Denver may be able to snag him at a relative discount compared to what he probably should be commanding on the open market. Conversely, if Harris returns to form and dominates the slot like he has since entering the league, he may just price himself out of Denver all together.

#2 Brandon Boykin, CB, Philadelphia Eagles

One year younger and one spot higher than Harris, Brandon Boykin is the closest thing Philadelphia has to the Boogie Man. He is not the biggest or fastest corner out there, but some way, somehow, he always finds a way to wreck a game plan. Despite playing just 635 snaps – for reference, most top starting outside corners average 1,000-1,100 snaps in a season – Boykin still tied for second in the NFL for interceptions in 2014 with six. Richard Sherman had eight on 1,003 snaps.

Just like Sherman, Boykin does most of his damage with a superb combination of intelligence and instinct. Normal 5’9" cornerbacks would see facing Dez Bryant without safety help as a suicide mission, but Brandon Boykin is not a normal cornerback.





Take a closer look at Boykin’s alignment and pedal off the snap. Philly is in a Cover-0 look with no safeties over the top. Boykin is five yards off with inside leverage on the Cowboys’ most physically gifted receiver. There is only one rational play call in this scenario, and Boykin knows it – throw it up to Dez.





Teams with big jump ball receivers tend to be huge fans of putting said big receivers inside and running a fade or corner route from the slot to the sideline. Pay attention to any Lions, Bears, or Cowboys game, and eventually you will see this concept used. The thinking here is that with so much space between a slot receiver’s inside alignment and the sideline, the receiver should have more room to work with to position himself between the defender and the ball without getting pushed out of bounds. That is the intent, at least. Whether or not a cornerback as gifted as Brandon Boykin allows it to happen is a whole different matter.

Off the snap, Boykin takes a single step inside to protect himself from an in-breaking route and then flips his hips to run with the expected fade.





Kyle Orton, who is filling in for an injured Tony Romo in Week 17, begins to loft the ball up to Bryant without hesitation.





As soon as Bryant turns his head to look for the ball, Boykin knows it is safe to close on the route.





Once within a couple yards of Bryant, Boykin turns his head to locate the ball himself. Despite having a significant size disadvantage, he is able to easily track and break up Orton’s pass. Consider this test passed with flying colors.





When watching Boykin on tape, it becomes immediately clear just how adept he is at using his quickness and fluidity to give himself the best possible angle to undercut a route. Boykin did not just strive to be in position to make a tackle or discourage a throw; far from it, actually. In fact, Boykin almost looked like he wanted to be targeted. Eagles tape is full of snaps where Boykin seems to be beaten only to spontaneously appear in front of his man for a deflection or interception.





Possibly my favorite snap from Boykin in the entire year came in the Week 17 winner-take-all showdown against Dallas.





Boykin is aligned five yards off the line of scrimmage while being leveraged inside to give a man coverage look.





With the single high safety on the other side of the field, Boykin slightly cocks his hips towards the sideline during his backpedal in preparation to play the same slot fade route that the Cowboys ran multiple times throughout the game.





Boykin had been playing the slot fade all night by flipping his hips early to run with the route down field, so the Cowboys attempt to take advantage of that tendency by breaking back inside with a timing pattern. Once Boykin flips to play the fade, Miles Austin cuts inside on a quick slant over the middle. Orton is already in the middle of his release before Austin is even out of his break.





Just like every other team the Eagles faced in 2013, Dallas found out the hard way just how ludicrously fast Boykin can change directions. While lesser cornerbacks would be a yard or two behind Austin at this point, Boykin is already trying to undercut the route and end the game.





Spoiler alert: it did not end well for the Cowboys.





Boykin would of course not be able to pull off any of these ball-hawking feats without his truly special foot quickness and hip fluidity. Late in the first half against Dallas, Boykin pulled off some magician-like footwork to not only mirror a whip route back towards the sidelines, but also to get in position to undercut and intercept any pass thrown his way. It has been said before, but it needs to be said again – this kind of ability is rare (Ex. 1, Ex. 2, Ex. 3, Ex. 4).





So what keeps Boykin out of the top spot for slot defenders? Strength, or lack thereof. With such a small frame and not enough functional strength to keep receivers from outmuscling him, Boykin was physically dominated at times, both at the line of scrimmage and at the stem of a route (Ex. 1, Ex. 2, Ex. 3).

Perhaps the best example of Boykin’s relative lack of strength came against Cowboys rookie (now sophomore) Terrence Williams.





The All-22 might suggest that Boykin was simply juked out of his shoes by Williams’ release, but the broadcast replay paints a different picture. Boykin attempts to slingshot into Williams’ route just like any other corner worth his salt, but his strength fails him as Williams easily dislodges Boykin from his chest. Boykin cannot swing himself into position in time and resorts to holding on for dear life as Williams explodes down field. Had he been able to hold on for just a fraction of a second longer, Boykin might have prevented himself from getting trounced by a rookie.





Regardless of his physical shortcomings, however, Boykin is still one of the most feared defensive backs in the NFL. His ability to take away the football is second to none, and he will only get better as he continues to build strength in NFL conditioning programs. There is still one young defensive back that is already better, however. They call him the Honey Badger.

#1 – Tyrann Mathieu, FS/CB, Arizona Cardinals

Chris Harris is great, Brandon Boykin is fantastic, but Tyrann Mathieu is a Defensive Player of the Year Award waiting to happen. Even as a rookie, nobody else in the NFL was as good in the slot as Mathieu. His combination of fluidity, speed, technique, instincts, and versatility made him arguably the best rookie defensive player in the league until an unfortunate knee injury sent him to injured reserve. Before breaking down Mathieu in detail, however, one must first understand how Arizona used him in their suffocating defensive scheme.

The Cardinals under coordinator Todd Bowles are one of the most enjoyable defenses to watch in all of football. In a style that can only be called "complex simplicity", Arizona blends several different concepts into a single unit that can morph into virtually anything at a moment’s notice. Odd fronts, even fronts, press-man, press-bail, Cover-2, zone blitzes, and almost every other coverage and pressure package imaginable are all utilized by the Cards during any given game. They may not be the best at any one particular thing, but the Bird Gang is perhaps the most well-rounded defense in the NFL.

The engine that makes this team go, at least on defense, is versatility. Calais Campbell is one of the best defensive linemen in the league and can play everything from 5-technique defensive end all the way down to nose tackle. Daryl Washington – when not troubled by off the field issues – is a whirlwind at inside linebacker who can stop the run, rush the passer, and blanket receivers in coverage. Mathieu fits that mold and then some as the team’s young do-it-all safety/cornerback hybrid. In base packages, the Honey Badger will generally line up as the weak side safety and help bracket receivers deep down field. In sub-packages, Mathieu kicks inside to slot cornerback where he can be closer to the ball and let his talents flourish.

While Todd Bowles will call a little bit of everything depending on the situation in a game, the Cardinals bread and butter fastball is to rush four and drop seven men into coverage. However, Arizona does not utilize traditional zone drops, but rather a technique called "pattern matching". Instead of each player dropping to the center of a designated zone and waiting for a receiver to enter their area of control, defenders will "carry the seam" as receivers release into their routes. When receivers break in various directions, each defender has a responsibility based on the depth and direction of each break.

Take the still image below as an example. Patrick Peterson, Tyrann Mathieu, and Yeremiah Bell are all seven to eight yards off the line of scrimmage, each one of them over a Colts receiver. Mathieu’s slight outside alignment and cocked hips are a tip off that the Cardinals are in zone coverage, but Arizona could just as easily be in "man free" with a blitzing inside linebacker against an empty formation. Ambiguity is a weapon in this situation.





In reality, Arizona has dialed up a variation on pattern matching called the "box technique". Normally used against tight bunches of receivers, the box technique gives four defenders – each aligned in a corner of an imaginary box – an assignment for handling receiver releases that prevents themselves from getting "rubbed" by their own team mates. In the case of the image above, Karlos Dansby is responsible for the first underneath inside-breaking route. Bell is responsible for any inside-breaking routes behind Dansby or in the end zone. Mathieu’s job is to snuff out the first underneath outside-breaking route, while Peterson handles any deeper outside-breaking routes like corners or fades.

Giving each defender a contextual assignment rather than a rigid zone drop helps cut down on the effectiveness of rub routes at the cost of placing an enormous amount of strain on safeties and linebackers. Safeties in particular have to juggle not only bracketing receivers deep down field if either outside corner needs help, but also potentially covering any other receivers that get released by the underneath zones. One could also make the case that if Arizona did not have two stellar coverage linebackers in Dansby and Washington last year, this entire scheme would fall apart due to an inability to pick up in-breaking routes over the middle. Now that both of those aforementioned linebackers are no longer in the building, the Cards could potentially be looking at some serious regression defensively in 2014.

Back to the images: Take a look at how Arizona matches the routes for each Colts receiver based on their assignments. Dansby floats slightly towards the numbers as Fleener breaks outside while Bell mirrors him over the top. Because Fleener is the nearest inside receiver, both Dansby and Bell are responsible for shutting him down. Meanwhile, Mathieu and Peterson work together to lock down everything outside the numbers. T.Y. Hilton is the first receiver to break outside from his alignment in the slot, so Mathieu immediately picks him up as per his assignment. Peterson, as expected, plays the fade to the corner.





In motion, the play looks like a hybridization of zone and man coverage.

In a less confined field, Arizona’s pattern matching defense looks like the image below. Indianapolis is in 12 personnel – one back and two tight ends – with two receivers to the "field side" of the formation. Arizona counters with another ambiguous look that could be either zone or man. Strong safety Bell and left cornerback Jerraud Powers are stacked in a way that could tip off man coverage on both tight ends, but in reality they are likely pattern-matching to take the first and second out-breaking routes, respectively. Powers likely also has responsibility to trail any "go" or "post" routes from either tight end. On the other side, Patrick Peterson is the only man defender on the field while Dansby, Washington, and Mathieu patrol underneath. Mathieu in particular is responsible for the first out-breaking route to his side while free safety Rashad Johnson picks up anything deeper down field.





The Colts suddenly shift before the snap, prompting the Cardinals to respond. Daryl Washington signals his adjustments, switching sides with Dansby and sending Bell to a deep half.





Arizona is now giving a Cover-2 zone look, though the responsibilities are mostly the same for every player.





Off the snap, Dansby floats slightly towards the numbers to help carry the seam – in this case, T.Y. Hilton – up towards Mathieu and Johnson. In a traditional zone drop, Dansby would likely be staying closer to the middle and waiting for a receiver come to him rather than moving towards the seam himself.





Dansby keeps his eyes on Luck as he releases Hilton to the deeper defenders. No receivers have broken outside yet, so Mathieu keeps sliding down field with outside leverage,





Hilton begins to make his cut underneath Fleener on a deep out route. Mathieu recognizes Hilton triggering his primary assignment and makes a buttery smooth turn to play the route.

Andrew Luck’s pass was batted into the air and (hilariously) caught by Samson Satele, but the entire Cardinals secondary displays excellent coverage skills here. Every single receiver is blanketed down field.





The Cardinals defense’s ability to play multiple different coverages from the same look allows Todd Bowles to mix in a change up in between his fastballs every now and then. Just when Luck expects to catch Mathieu too far away to close on an underneath flat route from Fleener, Karlos Dansby charges towards the sideline and catches the Colts off guard. Luck restrains himself from throwing a second pick-six to Dansby in the same game, but the Cardinals unexpected shift in coverage leads to a nice clean up sack from the front four. This is a masterful call from Todd Bowles, if I do say so myself.





Mathieu needs exceptional physical skills to succeed in Arizona’s demanding system almost as much as he needs mental acuity. While not quite as smooth as Brandon Boykin, Mathieu is more than capable of locking down receivers with stellar footwork, quickness, and burst to the ball (Ex. 1, Ex. 2).





Despite still having room for improvement in footwork, Mathieu is already a seasoned pro when it comes to hand usage. Unlike Boykin, Mathieu excels at getting physical with receivers in the middle of their release and sling-shotting himself into position to make a play on the ball. The Honey Badger may be among the most diminutive defensive backs in the league, but he plays like a linebacker (Ex. 1, Ex. 2, Ex. 3).





Speaking of playing like a linebacker, easily the most exciting part of watching Mathieu on tape is seeing what he does against the run. To say that the young Cardinal is "slippery" is the understatement of the year. At times he simply could not be blocked. Mathieu is not big or strong enough to consistently shed blocks once engaged, but he is so quick and elusive that it is rare to see him properly blocked in the first place. He just has an uncanny ability to wiggle himself free and make a play (Ex. 1, Ex. 2, Ex. 3, Ex. 4).





As far as "weaknesses" go, Mathieu’s only faults in the charted sample size of tape were brief lapses in concentration. Whether he was trying way too hard to make a play and losing track of his receiver or simply flipping his hips just a little bit too early, none of Mathieu’s bad snaps could be considered anything beyond rookie mistakes. I do not expect said mistakes to turn into trends any time soon.

The Verdict

No two slot defenders are alike, even among the best of the best. Chris Harris is fast, physical, and experienced. Brandon Boykin is a feared turnover machine. Tyrann Mathieu is perhaps the most complete young defensive back in the entire league. All three of these young stars have different skill sets, schemes, strengths, and weaknesses, but every single of them carry the same warning label.

Target at your own risk.