by Derrik Klassen

Head coach Frank Reich and quarterback Andrew Luck are the centerpieces of the Indianapolis Colts' resurgence this season. The Colts would not be vying for a playoff spot without their high-flying offense. However, it is not the Colts' offense that has brought them to the Football Outsiders' spotlight this time around. A sight unseen in Indianapolis for many years, the Colts finally have some semblance of a defense, and they have been on fire over the past month and a half.

Over the past six weeks, the Colts hold the sixth-best defensive DVOA rating. That rating does not quite match the likes of the Ravens or Bears, but it is far better than most anyone would expect of a post-Robert Mathis and Dwight Freeney Colts' defense. In most contests, the offense has returned the favor and pushed the team to victory, only dropping one game in a disgusting 6-0 brawl with the Jaguars. The game quality now is better and more reliable than the shootouts the Colts were constantly finding themselves in from Weeks 1 to 10.

It is not often a defensive line flies under the radar when a defense is building steam, but that is where the Colts' group has arrived. A quick glance at the depth chart leaves you pondering if the biggest "star" is defensive end Jabaal Sheard, the most consistent five-sacks-a-year in all of football, or defensive tackle Grover Stewart, who you actually had never heard about before but are kind of interested in the idea that people in this generation are still being named Grover. It is a real who's who of … who and who?

Across the board, players have stepped up to collectively make the Colts' defensive line a quietly stingy group, particularly on the ground. At least in part, the added consistency can be attributed to some of the new coaching staff that entered the fray this season. Defensive line coach Mike Phair was an assistant for Lovie Smith in Tampa Bay and at the University of Illinois. In Phair's three years (2015-2017) at Illinois, the school produced three NFL defensive linemen in Dawuane Smoot, Carroll Phillips, and Jihad Ward. Granted, the professional success of that bunch is nothing to boast, but even getting three players from that school to the NFL over that span is impressive. In addition to Phair, former Colts edge rusher Robert Mathis is on staff as a pass-rush consultant, which has aided players such as Denico Autry and Kemoko Turay.

That said, if any one player is a testament to Phair's ability, it is Margus Hunt. Hunt was drafted by the Bengals in the second round in 2013, but never amounted to anything other than a field goal-blocking specialist in Cincinnati. This season, Hunt has dwarfed the production of the previous five years of his career, racking up 5.0 sacks and 13 tackles for loss, and has become especially helpful in the run game.

Any number of brute-force gashes through the A-gap where Hunt eats the ballcarrier could work to showcase his impact this year, but it is more worthwhile to look at some of the smaller plays that he does not necessarily make himself. Hunt regularly allows the Colts' young linebackers to thrive.

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Hunt (92) is lined up in the A-gap between the center and left guard for this play. The Jaguars want to "fold" Hunt by having the left guard block him inside while the center steps back and loops around to replace the left guard. This can be a good idea versus aggressive upfield players, but Hunt gets off the ball so quickly in this example that he is able to disrupt the center's path, forcing him to stumble and be a second or two late getting out in front of the running back. Colts linebacker Darius Leonard takes advantage of Hunt's disruption and flies to where the center should be, beating him there by a good margin. The runner is forced right into Leonard's waiting arms for a short gain.

This example is not to highlight Hunt as a standout of the group necessarily, but that a 31-year-old castoff can suddenly be a valuable player. That is a testament to Phair and the coaching staff. That caliber of performance over expectation is rampant across the entire defensive front.

Though the under-appreciated defensive line may be the most intriguing storyline, the glue to hold Indianapolis' front seven together is, of all things, a rookie linebacker. Leonard, a second-round pick out of FCS South Carolina State, is the new heart of the defense. Leonard is a capable athlete, but where he excels is in his decisiveness and savvy working between the tackles.

One of the "rules" of evaluating linebacker play is that the linebacker should be within 2 yards of the line of scrimmage when the running back gets the ball (2 1/2 if the quarterback is in shotgun) because it almost certainly means he has done his job to fill the right gap. Leonard finds a way to get within 2 yards on nearly every snap regardless of the play concept.

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This clip is slowed down to help visualize Leonard's recognition skills and closing speed. Right off the snap, Leonard (53) sees the two defensive linemen in front of him, Stewart (90) and Hunt (92), slant to the left -- the same direction the running back opens to. Leonard knows that the defensive linemen showing color to the back towards that side will force the running back to cut the play inside. Without hesitation, Leonard springs through into the path the running back has to go to without giving right guard Connor Williams (52) a chance to meet him at the second level. Leonard closes on the running back and brings him down with the help of a couple teammates.

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Again in slo-mo, Leonard effectively plays two separate gaps on this play, giving the illusion of covering one before working over to another. Leonard starts off the ball between the right guard (Williams) and tackle (La'el Collins, 71) and begins to slide down to cover that gap. The running back is intending to hit through that gap, but Leonard steps into it so quickly that it appears closed. As the running back cuts the play back the other way, Leonard grooves across the line of scrimmage to follow him and complete a joint tackle with his linebacker counterpart, Anthony Walker (50). Had Leonard not flowed over to help Walker in time, the running back may have been able to fall forward for extra yards, if not break the tackle altogether and take off.

Between the unheralded defensive line and a refreshing linebacker corps lead by Leonard, the Colts boast the fifth-best run defense in the league per DVOA. The defensive front also ranks sixth in adjusted line yards, sixth in second level yards, and ninth in open field yards. Running against the Colts is often a futile effort.

With that in mind, it is worth closely examining the schedule the Colts have faced on their defensive tirade over that past six weeks. Though it is reasonable to believe the Colts have actually improved, their recent slew of opponents could not have been a more perfect match given Indianapolis' defensive strengths. While the Colts have an excellent run defense, they hold a middling 19th-place position in pass defense DVOA.

Week Opponent Current Rank,

Run Offense

DVOA Current Rank,

Pass Offense

DVOA 11 TEN 13th 25th 12 MIA 11th 26th 13 JAX 20th 30th 14 HOU 28th 12th 15 DAL 17th 27th 16 NYG 21st 16th

Only two of the Colts' past six opponents feature better passing offenses than rushing offenses. Teams such as the Titans, Jaguars, and Cowboys are especially prone to leaning on their ground game over their passing attack, be that due to lack of quality quarterback play or a simple philosophic preference. It should come as no surprise that the Giants, one of the two pass-favored teams, gave the Colts a little trouble last week and produced the Colts' only below-average defensive DVOA performance of the past six weeks (9.3%). The Giants' 27 points on Sunday were the most the Colts had allowed over this stretch and one of only three 20-plus-point allowances.

That is not to say the Colts' secondary has been awful over this stretch and is only being carried by the front seven. Second-year cornerback Quincy Wilson has flashed great moments of play in press coverage; cornerback Kenny Moore III has been decent when necessary and a lethal slot blitzing option; and safety Clayton Geathers has been a menace in the box and when operating in short areas of the field as the YAC police. Without a threatening pass rush, though, the secondary can get left out to dry, and they are not a strong enough unit to make up the difference. Even on their best day, the Colts' defense is very much still centered around their ability to win the ground war.

If the Colts find themselves pitted against the Baltimore Ravens at any point along the way, they will be perfectly equipped to handle that style of run-first football. However, as is representative of the state of the league, many of the other AFC playoff teams are passing powerhouses, ranging from the veteran-led Patriots and Chargers to the youthful Chiefs and Texans.

The Colts' playoff path will look vastly different from the streak of games that contributed to their defense's sudden rise to prominence. Having a better defense now than they did early in the year will certainly help the Colts, but the nature of this six-game run makes it fair to question how they will fare against a different, more pass-oriented offensive landscape come January.