We're seven weeks into the NFL season, and there's only one team who has both a top five offense and defense in the league this year: the Indianapolis Colts. The Colts are the number one offense in terms of yards per game gained (452.9) and are the number three defense in terms of yards per game allowed (311.1). The Colts are the number two offense in terms of points per game scored (30.9) and the number four defense in terms of points per game allowed (19.4). Indy is the only team in the league with a top five unit in both offense and defense so far this year.
The Colts' defensive dominance this season has been well documented. They're fourth in the NFL in points per game allowed and third in yards per game allowed. They're first in third down conversion percentage allowed (26%) and tied for fifth in fourth down conversion percentage allowed (20%). They're tied for third in the league in sacks recorded (21) despite not having last year's sack champion, Robert Mathis, for a single down this season. The numbers over the past five weeks are even more staggering, including allowing just 8 third down conversions in 51 attempts (15.7%) and just one each in the past four games.
Taking a look at the chart, you can notice that the Colts have recorded 21 sacks this year and forced 11 turnovers in pass defense (they've forced 12 turnovers total - 11 in pass defense and 1 on special teams). In other words, get this - on one out of every 12 drop backs the Colts sack the opposing quarterback and on roughly one out of every 23 drop backs the Colts force a turnover. That's some pretty good defense.
The Colts have done it against some good competition, too. They've played four of the league's top-twenty passers (in terms of yards) and all but one of them (Nick Foles) threw for less than his season average yards per game against the Colts. The Colts have played against seven of the league's top-twenty receivers and five of them were below their season average in yards per game against the Colts. Overall, the Colts' pass defense is ranked fifth in the league, allowing 214.4 yards per game through the air. They've allowed the third fewest touchdown passes against them (8) and the 4th lowest opposing passer rating (79.0). We know that the Colts' pass defense has been their strength this year - but what is the key to the defense's terrific success this season?
You could make a good case that the key has been defensive coordinator Greg Manusky, and if you did I wouldn't disagree. He has done a tremendous job, and he's certainly deserving of recognition. You could make a case that guys like Cory Redding or Jerrell Freeman have been instrumental in the defense. But the biggest key to the Colts' defensive success recently and this entire season has been the play of their cornerbacks.
Vontae Davis has had a fantastic season. Not that Pro Football Focus's grades are everything, but this year Davis is their highest graded cornerback - that counts for at least something. Also per PFF, when opposing quarterbacks target Davis they have a passer rating of just 35.2, the second best number in the league (Denver's Chris Harris is first with a 33.5 opponent passer rating) and the next closest to Davis is a full 16.3 points behind. Davis has allowed the fourth fewest catches (32), the fifth fewest yards (174), is tied for the fewest touchdowns (0), and is tied for the sixth most interceptions (2) among those who qualify (in PFF's database). He has truly achieved shutdown corner status this season, and he has more than lived up to the big contract he received this offseason. Give Davis major credit - it isn't often that you see a player get paid and then still improve in the offseason, but that's exactly what he did and he has become the biggest key to the Colts defense.
But it's not just him - it's the cornerbacks as a whole. Davis is clearly the best among them, but Greg Toler has done a solid job too. According to PFF (and I honestly didn't mean to go all PFF on you in this article), Toler has the eleventh best opponent passer rating with a 66.6. This is a guy who many have differing opinions on - all the way from some saying he's terrible to others saying he's great. I'm at neither of those extremes, but I also realize the importance he plays in the Colts' defense. He's the corner opposite of a shutdown guy, so he's going to get thrown to more, and indeed that has been the case. In the scheme the Colts run, they need a guy who can play man coverage and be left alone there at times. Davis fits this perfectly, and Toler is a helpful compliment to him. I think that Greg Toler has had a good season and has had more of an impact on this defense than some might think, which I'll get to in a minute.
Lastly, Darius Butler has been tremendous. His passer rating allowed of 87.8, while seeming very high, is actually sixth best among slot corners this year (per PFF). Butler has been among the best nickel corners in the NFL, and the Colts have missed him in the past two weeks when he has been out. He too has been having a very good season and has helped the Colts out a lot.
Not only is Vontae Davis arguably the best player on the Colts' defense and not only do the pass defense numbers back up the claim that the cornerbacks are the key to this Colts defense, but here's perhaps the most important thing: the cornerbacks allow the rest of the defense to do what they've been doing. Greg Manusky has been widely praised for his blitz schemes and for manufacturing pressure without a star pass rusher, and that credit is incredibly deserved. But Manusky is able to dial up many of these blitzes because he has corners he trusts to play man defense one-on-one and hold their own.
A perfect (and extreme) example of this came on the very first series in last Sunday's game against the Bengals. On the first third down attempt of the game, Manusky ran what was a "cover zero" blitz. What this means is that he sent the house and left the corners one-on-one with no help whatsoever, blitzing everyone else. As you can see, it worked. [Note: start the "slider" on the left side of the picture and then move to the right to see the before the snap and during the snap pictures.]
<p><div class="image-compare-tool ICT-sbnation"><div class="image-compare-images"><div class="image-compare-bottom"><img src="http://cdn3.vox-cdn.com/uploads/chorus_asset/file/2382202/cover_zero_blitz.0.png"></div><div class="image-compare-top"><img src="http://cdn3.vox-cdn.com/uploads/chorus_asset/file/2382206/cover_zero_blitz_2.0.png"></div></div></div></p>
As you can see, the cornerbacks stayed with their receivers. Granted, they didn't have to be in coverage long because, when you're rushing that many guys, you're going to get pressure. But this is a risk that Manusky wouldn't have been able to take without the trust in his cornerbacks to play man defense without safety help over the top.
We've also seen the Colts' third down defense be successful in large part because of the coverage. Maybe these two pictures aren't the best examples, but they illustrate something that is seen over and over again on the tape - the Colts' coverage has been good this year, and that has helped on third down (which both of these pictures are from).
Again, maybe these aren't the best examples, but the principle remains: the Colts cornerbacks have been the key to what Indianapolis has been doing defensively. The pass rush, while not taking anything away from great individual efforts from guys like Cory Redding or Bjoern Werner, has been helped out overall through blitzes, which have been enabled by the cornerbacks. The run defense, which is improved from a year ago (though still not great), has been helped by the cornerbacks, as their play gives Manusky the option to commit more players toward defending the run. Not only have the corners been the most consistent and best unit on the Colts' defense this season, they've also been the key to the recent success that the unit has had.
All screenshots are taken from NFL Game Rewind.