The 2021 NFL regular season is in the books, and in a little over a week, the postseason will join it. The NFL teams have already begun to break down and look back on the last season of action, and we at numberFire are no different.

At numberFire, our play-by-play tracker records 12 different types of pass routes. I have taken a look at each of them from the 2021 season to try and find out which quarterbacks enjoyed throwing which routes, as well as who enjoyed the most success and efficiency on a per-play basis. For ease of reading (and researching), I have combined the returns for wide receiver screens and all screens. The results have made for interesting reading.

Quarterbacks must have attempted at least 10 passes on the various routes to be included in the dataset, and all route data comes from Sportradar. Let's dive in.

The Post Route

For the second year in a row, Matthew Stafford led all quarterbacks in throwing post routes. The Los Angeles Rams quarterback attempted 45 such passes, completing 28 for a league-high 720 yards and 7 touchdowns. He was also tied for the lead with four interceptions.

It was the quarterback for the other LA team who boasted the most efficiency when working the post route, though. Justin Herbert of the Los Angeles Chargers averaged 1.35 Passing Net Expected Points (NEP) per drop back on this particular route, completing 11 of his 17 attempts for 348 yards, 3 touchdowns, and 2 interceptions.

The Go Route

We have another repeat leader, with Ben Roethlisberger once again leading the league in nine routes thrown. The Pittsburgh Steelers quarterback sent 52 of these passes down the field, completing 18. These 18 completions garnered 530 yards and 4 touchdowns but also generated 3 interceptions. Out of 35 qualifying quarterbacks, Roethlisberger's 0.16 Passing NEP per drop back was 24th.

Joe Burrow led the league with 727 yards and 11 touchdowns on this route while also setting the efficiency pace with 1.08 Passing NEP per drop back. Only one quarterback threw more interceptions than Roethlisberger, and that was Jalen Hurts. Hurts tossed four picks on the go route, nearly half of his season tally of nine.

The Curl Route

It must be something about rookies and the curl route, as for the second year in a row, a first-year quarterback led the league in this particular category. In 2020, it was Herbert setting the pace. Trevor Lawrence took the honors this year. He completed 76 of his 102 attempts for 679 yards. He didn't throw a single touchdown but did register two interceptions.

Herbert showed that he hasn't completely lost his knack for throwing the curl, as he led the league with five scoring passes. The most efficient passer was Tim Boyle. He completed 10 of 13 attempts for 99 yards and a touchdown, and he averaged 0.64 Passing NEP. Behind him was Patrick Mahomes, who averaged 0.51 Passing NEP on his 75 attempts.

The Comeback Route

As unproductive as he was at throwing the go route, Hurts enjoyed much more success with a route that saw his receivers come back to him. The Eagles quarterback led the league with 36 attempts for 366 yards. He was second in Passing NEP per drop back with 0.60, trailing only Stafford, who averaged 0.92.

Josh Allen was the only quarterback with multiple touchdowns on the comeback, throwing two. Allen also led the way with three interceptions, ahead of Burrow, Baker Mayfield, Kyler Murray, and Taysom Hill. They threw two each.

The Corner Route

Lawrence led all comers with 17 completions on 35 attempts. He was fifth with 313 yards, with Mahomes leading the league with 459 yards. Mahomes threw a single touchdown pass on the corner route, a long way behind the trio of leaders. Aaron Rodgers, Kirk Cousins, and Tom Brady threw five each, with Brady the only one of the three to toss an interception on this particular route.

Along with five touchdowns, Cousins was the most efficient exponent of the route, averaging 1.29 Passing NEP. Mahomes was second at 1.16.

The Crossing Route

Carson Wentz attempted 50 passes on crossing routes, completing 33 for 332 yards, 3 touchdowns, and 2 interceptions. The only player who was taken before Wentz in the 2016 NFL Draft, Jared Goff, was the other player with at least 30 completions and 300 yards on this particular pattern.

Mac Jones led the way with four touchdown passes on crossers, while Teddy Bridgewater was efficiency personified when he looked that way. The Broncos quarterback completed 17 of his 18 attempts for 156 yards, 2 touchdowns, and 0.95 Passing NEP per drop back.

The Slant Route

The slant route was a particular favorite of Herbert, who led the league with 79 attempts and 49 completions. Herbert's 425 yards trailed only Roethlisberger (459) and Jimmy Garoppolo (432) on slants, but he was 34th of 37 qualifiers with -0.10 Passing NEP per drop back ahead of just Zach Wilson, Jacoby Brissett, and Cam Newton.

Brady led the way with nine touchdown passes on slants, while Roethlisberger, Ryan Tannehill, Mahomes, and Herbert all tossed two picks. Tyler Huntley completed 9 of his 10 attempts on the route, averaging 1.40 Passing NEP. Derek Carr averaged 1.13 on his 24 attempts, with 22 completions for 257 yards and 2 scores.

The Out Route

Lawrence ended up ahead of the pack in yet another category, throwing 90 out routes while completing 50. Herbert led the way with 58 completions and 577 yards while Cousins and Rodgers tossed 6 touchdowns each. Stafford and Goff each tossed three picks on out route pass plays, once again linking these two in NFL lore.

It was quite an efficient route for the Cardinals' quarterbacks to throw, as Colt McCoy and Murray finished first and second in Passing NEP per drop back on the out route. McCoy averaged 0.77 Passing NEP on his 12 attempts while Murray was not too far behind with 0.58 on his 27.

The Flat Route

No one worked the flats more than Aaron Rodgers in 2021. He led the league with four touchdowns on this route in 2020, while this time around he set the pace with 87 attempts, 76 completions, and 527 yards. He once again tossed four scores to this area of the field, but he trailed Bridgewater, who managed six.

Sam Darnold was one of eight quarterbacks to throw an interception to the flat but was the only one to manage it twice in 2021. He was last among all qualifiers with -0.49 Passing NEP per drop back. At the other end of the scale, San Francisco 49ers rookie Trey Lance was the most efficient in terms of Passing NEP per drop back with 0.47.

The In Route

Tom Brady completed 32 of his 53 passes on in breakers in 2021, amassing 385 yards and 3 touchdowns. While no other quarterback could match his attempts and completions, Herbert and Stafford matched his touchdown tally while his former understudy, Garoppolo, was the other player with more yards. Garoppolo also led the league with three interceptions, tied with Darnold.

Rodgers led the way with 0.97 Passing NEP per drop back, but Zach Wilson was second with 0.82. This would appear to be an area in which Wilson can succeed. Perhaps the Jets would like to allow Wilson to target this route more often in 2022, as 25 other players attempted more in breakers than Wilson, who was held to just 16.

Screen Passes

Three quarterbacks attempted at least 50 screen passes in 2021, with Cousins leading the way with 57. Brady completed 50 of his 54 attempts while Kyler Murray led the league with 370 passing yards on such plays. Murray attempted 46 screens in 2020, too. Goff threw three touchdowns on screen passes, while Murray, Taylor Heinicke, Andy Dalton, and Burrow all threw an interception on a screen pass.

The most efficient screen passer was Mayfield, who completed 31 of his 35 attempts for 349 yards and a touchdown. Mayfield averaged 0.61 Passing NEP on screens, a far cry from Russell Wilson, who struggled with the route. Wilson averaged a mere -0.31 Passing NEP on his 27 attempts, gaining 87 yards.