September 29, 2021

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Adjusted Interceptions 2020 | Football Outsiders

6 min read
Adjusted Interceptions 2020 | Football Outsiders


Officially, the NFL’s interception leaders last year played for Denver and Philadelphia, but one of those quarterbacks was largely a victim of bad luck. Other unlucky quarterbacks played in Seattle and Minnesota, while the football gods smiled on quarterbacks in Pittsburgh, Arizona, and Miami.

Today we are going to discuss adjusted interceptions. Unlike the NFL’s raw interception totals, these numbers account for plays when a defender drops a pass that he should have caught, or when a wide receiver makes a big play to turn what should have been a turnover into an incompletion instead. On the other hand, sometimes quarterbacks are charged with interceptions that aren’t really their fault—passes that bounce off a receiver’s hands and straight to a defender—or interceptions that don’t matter, like Hail Mary passes.


How it Works

After each season, we go back and account for these discrepancies and tabulate each quarterback’s adjusted interceptions. Here’s the process:

  • We start with each player’s actual interception total. Denver’s Drew Lock and Philadelphia’s Carson Wentz tied for the league lead in this category with 15 apiece in 2020.
  • 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 had 10 such plays last season, most in the league; Kyler Murray, Sam Darnold, and Nick Foles were tied for second with nine each.
  • Next, we subtract those interceptions that were tipped by receivers into the hands of defenders (as established in 2017, these plays can be thought of as Matt Ryan specials). Derek Carr, Daniel Jones, and Russell Wilson tied for the league lead in this department with two each. We also subtract passes that are tipped by receivers but then dropped by defenders to make sure they are not double-counted. There were only four of these in 2020; no player threw more than one.
  • 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, but this year there was only one play that was in the gray area: a Wentz interception in Week 5 against Pittsburgh, thrown on fourth down while trailing by nine points with 2:18 to go, which we counted as a Hail Mary interception. Kirk Cousins led all players with three Hail Mary interceptions last season.
  • We subtract dropped interceptions that occur in Hail Mary situations, since those plays wouldn’t count as adjusted interceptions even if they had been caught. Cousins, Darnold, and Lock each had one of those throws.

Long-Term Trends

When we started running these numbers, we had to get the data from our own in-house volunteer game charters. For the last six seasons, we’ve had access to data from Sports Info Solutions. 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.

Officially, only 2.2% of all passes thrown in the NFL in 2020 were intercepted, the lowest rate for any season in the record books. That number has been trending downwards for years—decades, really—but one reason it bottomed out was that defenders all over the league developed a severe case of butterfingers. There were 236 dropped interceptions last season, most of any year in our records going back to 2007. Dropped interceptions have actually been climbing for several years now, even as official interception numbers have plummeted. The leaguewide adjusted interception rate was 3.4%, the highest in any season since 2012.

Note that we didn’t start counting “tipped and dropped interceptions” until 2012 and “dropped interceptions that occur in Hail Mary situations” until 2019, which is why no numbers are listed in those categories in earlier seasons.

It looks like quarterbacks haven’t gotten any better at avoiding interceptions, but defenders have gotten worse at reeling them in. Given the critical value of turnovers in the game of football, this seems like something defenses should be working on more in practice. Anyway, as a result of these trends, the average quarterback threw about 50% more adjusted interceptions than actual interceptions, up from the usual rate of 30% or so.


Individual Leaders

When we run these numbers for Lock and Wentz, the interception co-leaders of 2020, we get very different results. Lock had 15 interceptions, but when we add five that were dropped, and subtract four more (two on Hail Marys, one that was tipped by a receiver, and one dropped on a Hail Mary), we get 16 adjusted interceptions—still in the top 10, but not at the top of the pile. The math for Wentz is simpler: we add seven drops and subtract one turnover on a Hail Mary and get 21 adjusted interceptions, most in the league. That’s a remarkable feat for a quarterback who was benched for the last four games of the year. Only one passer has ever led the league in adjusted interceptions on fewer throws, and that comes with an asterisk: in 2018, Sam Darnold threw 21 adjusted interceptions, tied for the league lead with Patrick Mahomes, on only 413 passes.

Two players tied for second behind Wentz with 20 adjusted interceptions: Pittsburgh’s Ben Roethlisberger and Arizona’s Kyler Murray. As noted earlier, Roethlisberger led all players with 10 dropped interceptions, and Murray was just one behind him. Add those 10 picks to Roethlisberger’s 10 interceptions that weren’t dropped and you get 20. Murray threw 12 interceptions with nine drops, but we also subtract one that was tipped by a receiver to get his total of 20.

Though Wentz led the league in adjusted interceptions, it was his old teammate Nick Foles who had the highest adjusted interception rate (minimum 200 throws). Foles threw eight interceptions with nine more dropped in only 311 throws, a rate of 5.5%. Foles is followed by Darnold (5.3%), Ryan Fitzpatrick (4.9%), Wentz (4.8%), and another Chicago quarterback, Mitchell Trubisky (4.7%). The Bears actually led all teams with 31 adjusted interceptions, which largely explains why they traded up in the draft for Justin Fields. (The Eagles were second with 29—21 by Wentz, seven by Jalen Hurts, and one by Nate Sudfeld.)

Derek Carr was the league’s best passer at avoiding interceptions, with an adjusted rate of 1.9%. The next five names behind Carr include four quarterbacks with Hall of Fame-caliber performances (Aaron Rodgers, Deshaun Watson, Patrick Mahomes, and Tom Brady) and also Gardner Minshew, who excels at avoiding turnovers and is below average at pretty much everything else.


Interception Luck

When we chart adjusted interceptions against actual interceptions, we see which quarterbacks were unlucky when it came to interceptions (those above the line) and those who benefited from good fortune (below the line). And it’s very clear who the most unlucky quarterback of the year was (click to open a larger image in a new window).

Adjusted Interceptions 2020

Minnesota’s Kirk Cousins threw 13 interceptions, tied for third-most in the league, but had only four dropped, which left him outside the top 25 in that category. Jacksonville’s Jake Luton had more interceptions dropped than Cousins (five) despite throwing over 400 fewer passes. And then there’s Cousins’ league-high three interceptions on Hail Marys. Cousins finishes with only 12 adjusted interceptions, making him the only full-time quarterback whose interceptions went down after adjustments. (It also happened to New England’s Jarrett Stidham in limited action—in 44 throws, he had three interceptions but only two adjusted interceptions.)

Other unlucky quarterbacks include Lock (who threw 15 interceptions with only five dropped) and Russell Wilson (who had two interceptions tipped by his teammates, nearly as many as the three passes that were dropped by defenders).

Three players also stick out from their peers on the other side of the line, meaning they finished with fewer interceptions than expected based on their adjusted interceptions would suggest. Two of them (Ben Roethlisberger and Nick Foles) we have already discussed in detail. The third was Miami rookie Tua Tagovailoa, who threw five interceptions with eight dropped for a total of 13 adjusted interceptions in only 287 passes. Tagovailoa’s adjusted interception rate (4.5%) was 2.8% higher than his raw interception rate (1.7%); only Foles had a higher gap among qualified quarterbacks.

https://www.footballoutsiders.com/stat-analysis/2021/adjusted-interceptions-2020