Week 6: Colts Defense by the Numbers

Each week during the season, I will be walking through the data from the previous Colts game analyzing the numbers to form a sort of “what happened” narrative as well as comparing the Colts against all other teams in the league. For a glossary of the stats listed, reference Season Stats. Thanks to Pro Football Reference, NFL.com, Football Outsiders and the nflFastR project for being awesome sources of weekly data.

I don’t judge a team by how they started or how they finished, but rather by their overall effort. Last Sunday, the Indianapolis Colts defense let one of the least successful offenses in the league put up almost 400 yards and 27 points. This was a bad performance.

Yes, I get that they only allowed 3 points in the 2nd half and that the Julian Blackmon interception sealed the victory, but prior to that, they gave the store away. People always like to recite the mantra “good enough to win”, well, this defense played poor enough to lose.

TEAM TOTALS

Most of the critical stats have the defense around 18th. EPA/play was an exception at 24th and that’s not a stat you want to be bad at.

I’m going to dive into first down conversion rate (1st/ply) as it really tells the narrative for the week. The defense held the Bengals to a 27.8% first down conversions, which is the 10th worst for any offense. However, the Colts also gave up a 75.9% DSR rate which is the 12th best for an offense.

Both of those stats are a measure of how well a team moves the ball so why are they so different? The reason is because the Bengals used a lot of plays per series (4th most) to achieve their first downs, deflating their conversion rate relative to DSR, which doesn’t care about play count.

The high number of Bengal plays was because they were forced into 3rd down situations on 17 of their series, tied for most of any team. And the high number of 3rd downs was a result of a stout Colts defense on 1st and 2nd downs, limiting Cincinnati to a 22nd ranked average yards and 20th ranked conversion rate on those plays.

All of this is good news for Indy and sets the defense up for huge success. However, they executed poorly on 3rd downs, letting 47% convert (11th highest) with an average of 9.4 yards gained (3rd most). This let the Bengals move the ball down the field (high DSR) even though their conversion rate was relatively low.

In other words, the defense did well in a stat that usually has more significance, but in this particular game did not, which is disappointing as they have been 3rd best at preventing conversions on the year. Here is the opponent conversion rate broken out by week.

PASS TOTALS

The Indianapolis defense made a bad passing offense look good. By overall value efficiency, Joe Burrow ranked 6th best on the week (0.31 EPA/db). His other key stats didn’t rank quite as high but were still good (10th PSR, 10th NY/db).

His first down conversion rate (1st/db) was 13th, which is lower than what Baker Mayfield did to the Indy defense in week 5, but is still not a good defensive effort. Here’s what each opponent looked like by week.

I miss weeks 2 through 4.

RUSH TOTALS

I find it hard to talk about rushing when the Bengals did so well through the air, but sure, we were bad at stopping the run too.

You could point to 3.1 yards per carry and claim victory, but that ignores situation. By EPA per carry the Bengals had the 6th best efficiency on the ground and that was mirrored with a 5th best success rate (RSR). That was primarily driven by 3 rushing TDs given up.

At least, the defense kept a low rushing first down conversion rate, which they have been good at all year (3rd best).

CONCLUSION AND LOOK AHEAD

I can find the cloud around every silver lining and the defensive performance this week was that. Sure, we won and of course they were lights out in the 2nd half, but against a 27th ranked offense (DVOA) they forced a 38 year old QB in his 6th game with a new franchise to put the team on his back.

That is not a sustainable formula for victory. Do better.

Next week my liver will enjoy a well deserved bye week. Just kidding liver, no weeks off for you. In week 8, the defense will face Matt Stafford and the Detroit Lions. Football Outsider’s ranks their offense 19th by DVOA and I have them 14th by points per drive and 17th in DSR. So, I think we are seeing the same range of meh-ness.

Stafford has not been good, ranking 20th by DYAR and 21st in EPA/db. He also ranks 21st in passing conversion rate, whereas the Colts defense ranks 3rd against. I like the sound of that.

Their run game is a bit better (13th DVOA, 11th EPA per carry), but that has not translated into consistent success (26th RSR, 20th 1st/c) .

Colts are early favorites (-3.0).