As the NFL slowly evolves schematically, much has been made about the invasion of the college game and the spread offense into the professional ranks. While it's true that many elements of the old school style of smashmouth football are still alive and well, the NFL a a whole has become increasingly pass-happy on offense. Naturally, there has been a response by defenses to combat this.

Nickel and Dimin'

According to Pro Football Focus' game-tracking data, there were 34,661 total snaps during the 2013 season. On 45 percent of those snaps (15,697 times), teams utilized a nickel defensive personnel package, i.e. five defensive backs on the field. It's a departure from the long-standing paradigm that featured two cornerbacks and two safeties. A further 12 percent of snaps (4,034) featured a dime package, or personnel groupings with six defensive backs.

In other words, the term "base defense" has become a misnomer, as coordinators league-wide have taken to running some version of their nickel/dime looks over 57% of the time. The term 'starter' is becoming archaic at some positions. The slot cornerback is its own position. The "3-down" front-seven player is becoming more rare.

It's a subpackage world.

History

Without delving into the specifics, nickel and dime defenses emerged in part as a response to the development of the modern pass-catching tight end. These athletic freaks of nature -- Kellen Winslow and Mike Ditka for example -- were too fast to be covered man-to-man by your prototypical 250-pound belly jersey-clad meathead linebacker, so defensive coordinators began substituting more-nimble defensive backs in to take their place.

Nickel and dime packages, and all the countless variations therein, have also evolved in response to the NFL offensive template personnel grouping that features three wide receivers, a tight end, and a running back. Unless you have amazingly talented linebackers capable matching up with receivers or even some of these 4.4-running tight ends, you should probably attempt to cover them with a safety or corner or be ready to get burned.

The term nickelback was born.

NFL Films' executive producer Greg Cosell elucidates on the background:

The idea that a team's third receiver was better than the defense's third, or slot corner, became a prevailing concept as the NFL advanced in the first decade of the 21st century. It was spread offense, NFL style. It clearly opened up more options with better matchups in the pass game, but "11" personnel - one back, one tight end, three wide receivers - offered much more than that. It provided the full playbook with all its dimensions. You still had a strong side running game with a line of scrimmage tight end, and you had 7 man pass protection concepts (five offensive linemen, the back, and the tight end) if you felt you needed it against a pressure, blitzing defense. High volume and favorable matchups: offensive coordinators liked the tactical opportunities "11" personnel presented, and more importantly, it afforded answers to any defensive problems. Defenses responded. Slot corner, by necessity, continued to gain in importance and value. That player was not just your 3rd corner; in fact, often one of the starting corners moved inside because his skill set better fit the demands of the position. Think Charles Woodson in Green Bay, Antoine Winfield in Minnesota. The overriding point was that defensive coordinators predominantly matched up to "11" personnel with their nickel sub-package (at times dime, if it was third-and-long). They could then focus on dealing with it schematically. That strategic chess match, with all its permutations and variations, has been compelling to watch over the last 10 years or so.

Adaptation

The Seahawks are a nice example for this article, and not just because they're the primary team I cover. Seattle plays in the NFC West, which among all divisions, sits at the vanguard for the old-school smashmouth faction still operating in the league. NFC West teams love to run the ball and the Seahawks love to defend the run, so for Seattle their base defense actually was their base defense. Not by a whole lot, though, as they ran their nickel/dime looks on 42 percent of their 1,180 total defensive snaps.

Even though the Niners, Rams and Cardinals are their main adversaries, Seattle had to get through New Orleans and Denver to win Super Bowl XLVIII. This required some flexibility and adaptability, personnel-wise.

Find the weakness and exploit it. You don't have to be Sun Tzu to figure that out.

The contrast between the speed and technical finesse needed to beat the Saints' high-octane passing game in the Divisional round game and then the great amount of grit and physicality needed to beat the Niners in the NFC Championship Game was visually striking. Adding another layer to the canvas was that Seattle combined both speed and power in the Super Bowl to stifle the greatest offense ever assembled.

They did so with multiplicity in base, nickel, and dime schemes, and varied personnel groupings.

Examples

For all you visual learners, let's take a look at a few examples from Seattle's 4-3 defense. Against the Broncos in the Super Bowl, Seattle ran in mostly nickel/dime looks, but did mix in some base schemes. At the end of the day, one of the Hawks' main goals on defense is to stop the run, and because the Broncos almost never run out of anything but 11 personnel (three wide receivers, one tight end, one back), it's not like they can just react to Denver's grouping when determining their defensive personnel.

Below, Seattle comes out in their base personnel on a Denver first-down. You can see what happens when you have base defensive personnel against a three wide receiver offensive set: K.J. Wright across from Wes Welker (left side of the formation in the slot).

To mitigate this obvious mismatch while still hoping to stop the run with base personnel, Seattle runs a zone coverage scheme, meaning Wright isn't required to run in man-to-man with the much shiftier, speedier Welker.

Wright is no slouch in coverage -- in fact, he matched up well against Jimmy Graham a few weeks prior -- but against Welker, it's not the look they are hoping for.

Now, contrast with Seattle's nickel defense. You can see Walter Thurmond now swapped in for K.J. Wright, playing up on the line against Welker.





In this particular example, Welker beats Thurmond in man coverage, but it illustrates just how difficult a job the slot cornerback or nickelback has. They don't have the sideline to act as an extra defender -- they must have the foot speed and change of direction ability to keep up with a receiver that has the distinct advantage of knowing where he's running.

The 3-4 base vs. nickel looks are similar but obviously slightly different. The Niners, for example, ran nickel & dime at right around the league average of 57 percent of the time despite playing the NFC West.

Below, you can see Aldon Smith flexed out onto the slot receiver in Seattle's three-WR set.





The Niners run a zone coverage, and the Seahawks run.

While Aldon Smith is surprisingly adept in space, it's certainly not his specialty. He belongs on the line of scrimmage disrupting run lanes or blowing up the QB.

That's where the nickel package comes in. In the Niners' standard look, though, they leave their linebackers in (because they're amazingly good), and swap out one of their down linemen:





For illustrative purposes, there are certain disadvantages to playing with a 190-pound defensive back instead of a 285-300-pound defensive end or tackle. If you're removing that player from the box, it can open things up in the middle a bit.

Nickel/dime looks can vary wildly. You can simply swap out a linebacker for a safety or corner. Depending on down/distance and game situation, you may be highly expecting a pass, in which case you can substitute in your best pass rushing defensive linemen.

The Seahawks never got overly exotic with their looks, but they rotated their front seven throughout the year. The player to log the most amount of snaps on the year was DT/DE Michael Bennett, who topped out at 57 percent of Seattle's total defensive snaps. He was followed by DE Chris Clemons (54 percent), Cliff Avril (52 percent), Clint McDonald, Tony McDaniel, and Brandon Mebane (50 percent), Bruce Irvin (47 percent), Malcolm Smith (46 percent) and Red Bryant (46 percent). They rotated their defensive line and outside linebackers depending on down, distance, opposing personnel, and opposing team.

Advantages of playing nickel/dime

Romeo Crennell said it well:

"A competitive defense in this era must employ above-average coverage skills at most, if not all, of the seven of the linebacker/defensive back positions. You have to be able to cover. You've got to have guys that can cover. So you're looking at corners that can cover, linebackers that can cover and even safeties that can cover. And not only zone safeties but safeties that can go man-to-man. Because you have to be able to mix man in there. "So I think that's the biggest thing, particularly the linebackers, because in the formations the linebackers are going to have to walk out and cover a tight end or a back that's out of the backfield, and if they can't move and they can't cover, offensively they find that matchup they like right now and they go right at it..."

Find the weakness and exploit it. You don't have to be Sun Tzu to figure that out. The problem that defensive coordinators find is that even those linebackers that aren't total liabilities in pass coverage can get embarrassed by the likes of Vernon Davis, Darren Sproles, or Julius Thomas. You need 4.4 speed to match up with that, and this is where a nickel cornerback or big nickel safety comes in handy.

Nickel packages get a team's best athletes on the field, from the defensive line and back. Often these players have such great athleticism that they can cover, rush, and blitz. If you have multiple players like that, the options at a coordinator's disposal are fairly limitless. A nickel or dimeback can blitz off the edge after protections have been set, or can drop back into coverage, and the attack angles can be changed constantly. You can stunt with your nickel defensive linemen, you can drop them into coverage, or both. Your defense is faster. It's dangerous.

Maybe just as important in nickel situations, you can put your best pass rushers on the field in anticipation for a pass play. Seattle's nickel defensive line consisted of Cliff Avril, Michael Bennett, Clinton McDonald, and Chris Clemons. Their ability to disrupt Peyton Manning in the Super Bowl -- when Seattle went nickel nearly throughout --was indispensable.

Disadvantages of playing nickel/dime

Simply, nickel and dime packages tend to be less effective against the run because you're removing players that specialize in stopping the run at the point of attack for players that can run in coverage.

This can be a size thing, a power thing, a mentality thing, and/or a spacing thing.

The hybrids

In terms of the nickel/big nickel defensive back, there is a new class of hybrid that is emerging in the NFL who can both cover the pass and blow up the run. These are the most valuable to coordinators.

Kam Chancellor is the prototype, but Eric Reid and Tyrann Matheiu both emerged as excellent and versatile defensive backs in 2013. Other guys from the 2013 NFL Draft like D.J. Swearinger, Shamarko Thomas, and Matt Elam all fit the profile as hybrid players with multiple skillsets. HaHa Clinton-Dix, Calvin Pryor, Deone Buchanan, Dontae Johnson, Marqueston Huff, and Sean Parker, among others stand out to me this year as particularly versatile.

Similarly, there seems to be a new era of undersized but insanely athletic defensive tackles that are seeing more snaps and more success. This trend should benefit guys like Aaron Donald, Dominique Easley, Caraun Reid, Will Sutton, and gap penetrating but undersized defensive tackles in this year's draft. Like safety/corner hybrids, defensive end/defensive tackle hybrids have seen their worth skyrocket over the past few years. You don't have to look further than Michael Bennett, Lamarr Houston, and Arthur Jones in free agency this year.

Specialists in the new NFL

"The later you go in the draft, the more holes, limitations, flaws a player has," Cosell said. "Success becomes a function of how he's utilized. In era of sub-packages a lot of players contribute, even if they play 12-15 snaps per game. Often the key is finding/defining a role."

With the increased usage of subpackages, players with limited overall skill sets but one or two high-level talents can find themselves key roles. Perhaps a player is average elsewhere but is an excellent blitzer, or perhaps he struggles in coverage but defend sthe run extremely well; these guys can find themselves with key roles in certain packages.

As the inimitable Jeme Bramel puts it, "This is the era of specialization in the NFL. Slot wide receivers, third down running backs, goal line runners and pass catching tight ends are becoming more and more important of the success of today's offenses. The defensive side of the ball is no different. Situational edge rushers and pass rushing defensive tackles, linebackers leaving the field on passing downs and, of course, nickel corners. Because NFL offenses are operating out of multiple wide receiver sets more than ever, NFL defenses are specializing on passing downs more often in response."

If you're not a highly versatile, rounded every-down player or if you're a tweener, do one thing and do it really well.