Adjusted Interceptions 2016
by Vincent Verhei
As we do every year, it is time to look back at the charting data of last season, and see which quarterbacks threw the most interceptions -- and which should have thrown the most. Some passers benefitted greatly from butter-fingered defenders, while others just couldn't buy a break.
Before we get into the math, let's explain again how we arrive at our adjusted interception statistics:
- We start with each player's actual interception total. Philip Rivers led the NFL in 2016 with 21 interceptions.
- We then add plays where the quarterback threw a ball that could have or should have been intercepted but was not, either because the defender outright dropped the ball (which we have been tracking in game charting since 2007), or he had it knocked out of his hands by an offensive receiver (a "defensed interception," which we have been tracking since 2012). These are listed as "Drop/Def INT" in the table at the end of this page. Ben Roethlisberger led the league with 12 such passes.
- Next, we subtract those interceptions that were tipped by receivers into the hands of defenders. Russell Wilson was the victim of three such plays last year, more than anyone else.
- Finally, we subtract Hail Mary interceptions, as well as interceptions thrown in desperation on fourth down in the final two minutes of a game. (We're flexible on these definitions -- we also counted an interception thrown by Trevor Siemian on fourth down with 2:06 left in the game and Denver trailing 30-20.) These are listed as "HM/End Q4" in the table. Jameis Winston threw an NFL-high three such interceptions last year.
In the past, we have also tracked plays which bounced off a receiver's hands before being dropped by a defender, to make sure they weren't double-counted. There actually weren't any of these plays in 2016, so we have removed this column from the table this year.
When we started running these numbers, we had to get the data from our own in-house volunteer game charters. For the last two seasons, we've had access to data from both Sports Info Solutions and ESPN Stats & Info, and were able to take the time to cross-check for errors where they disagreed on plays. Determining whether or not a defender should be charged with a dropped interception will always be subjective on some plays, but you can rest assured that all the obvious calls have been counted here.
Those of you who have purchased Cian Fahey's Pre-Snap Reads Quarterback Catalogue should know that the numbers in this essay are different from the "interceptable passes" written about in that book. As Fahey explains, "An interceptable pass is any pass that should be intercepted because of something the quarterback did. If the quarterback throws an out route too far infield to the point that it hits the defender in his chest, that’s an interceptable pass. If the quarterback misreads a coverage and throws the ball to a spot where the defender has an opportunity to run underneath it, that’s an interceptable pass." Because the numbers in that book were based on the research of a single observer, Fahey was able to use much more subjectivity in his statistics while still maintaining consistent standards. Adjusted interceptions include fewer such judgment calls, and ask only whether a defender should have caught the pass, not whether he should have been in position to do so in the first place.
With the methodology explained we can finally get into the results, and thankfully those results are far more interesting than they were last year. In 2015, every quarterback finished with about as many interceptions as he should have. In 2016, however, some were much luckier than others.
We'll start with Ben Roethlisberger. The Steelers quarterback officially threw 13 interceptions, tied for 13th in the league. However, as we mentioned earlier, Roethlisberger threw a dozen more passes that could have been intercepted, but were dropped or broken up by his receivers. Adding those passes to the 13 that were intercepted leaves us with 25 adjusted interceptions for Roethlisberger. There are no other adjustments to make in the quarterback's numbers -- he didn't have any Hail Mary-esque interceptions, nor any that should have been caught by his receivers in the first place. That gap between 25 adjusted interceptions and 13 actual interceptions was the highest in the league last year. Even if we account for Roethlisberger's 524 pass plays (a number that does not include spikes or defensive pass interference calls, but does include things like sacks and intentional groundings), we end up with an interception rate of 2.5 percent, but an adjusted interception rate of 4.8 percent. That's the biggest gap in the league. In second place: Roethlisberger's contemporary from the 2004 draft class, Eli Manning of the New York Giants, who was second behind Roethlisberger with 11 throws that should have been intercepted, but were dropped by defenders. Manning's 26 adjusted interceptions were most in the league; Roethlisberger's 25 ranked second.
At the other end of the spectrum we find, of all people, yet another 2004 first-round quarterback. While defenders dropped 12 of Roethlisberger's passes and 11 of Manning's, they dropped just one would-be interception from Philip Rivers, even though with 21 actual interceptions he gave them plenty of opportunities. (There was a fourth quarterback drafted in the first round in 2004, but J.P. Losman hasn't thrown an interception, adjusted or otherwise, since his last NFL season in 2011.) Taking those 22 plays and subtracting two Hail Mary interceptions, and another that should have been caught by his receiver, and Rivers finishes with 19 adjusted interceptions -- still high, but tied for eighth instead of leading the NFL.
Rivers was one of three quarterbacks to finish with fewer adjusted interceptions than actual interceptions in 2016, along with former teammate Drew Brees and Case Keenum of the Rams. And here is where things start to get weird. We looked at historical trends in this piece last year and found that the quarterbacks with the worst interception luck since 2007 were … Drew Brees and Philip Rivers. Meanwhile, the quarterback with the best interception luck in that timeframe was Carson Palmer. In 2016, Palmer had the fifth-largest gap between actual interceptions and adjusted interceptions, behind Roethlisberger, Manning, Cam Newton, and Andy Dalton. Perhaps, at the extremes, we are measuring something more than luck here. Perhaps there is something about Rivers and Brees (or, more likely, the opponents they face) that makes it unusually easy for defenders to hang on to the ball.
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Meanwhile, in Chicago, Jay Cutler's replacements couldn't have had any more disparity in their interception numbers. Officially, Matt Barkley threw 14 interceptions in 216 passes, a rate of 6.5 percent that would have been worst in the league by a wide margin if had thrown the 224 passes needed to qualify for the NFL's leaderboards. (For the record, if Barkley had thrown eight more passes, even if none were intercepted, his rate would have been 6.3 percent, still much worse than Ryan Fitzpatrick's "league-worst" 4.2 percent.) Barkley also finished with 14 adjusted interceptions, in 222 pass plays in our methodology. Whichever system you prefer, it's obvious Barkley was a turnover machine in 2016. His counterpart, though, was a model of ball security. Brian Hoyer shattered the record books with precisely 200 passes without an interception -- 73 more throws than any quarterback had ever thrown before without delivering one to the other team. And that total doesn't change in adjusted interceptions. Hoyer had no throws that were dropped by defenders, or broken up by his own receiver. In fact, hardly anyone came close. Malcolm Jenkins tipped away a pass intended for Kevin White in Week 2, and Julius Peppers batted down a pass in Week 7. That's it: those were the only plays when defenders got their hands on a Hoyer pass all year. Hoyer also had the NFL's second-lowest adjusted interception rate in 2015, but threw more interceptions than usual in each of his prior NFL seasons.
The following table lists adjusted interception numbers for all quarterbacks with at least 200 non-DPI pass plays in 2016. Players are sorted from most adjusted interceptions to fewest.
|Adjusted Interceptions, 2016|
|Tip INT||Adj INT||Pass Att
|Tip INT||Adj INT||Pass Att
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Here's a look at adjusted interceptions in prior seasons.