-- After grading every player on every play over the course of the regular season, the Pro Football Focus analysis team has identified the most improved in several categories, from second-year players on both sides of the ball to overall passer and many more:
Second-year player on offense
Gordon struggled as a rookie in 2015. He averaged 3.5 yards per carry, ended with less than 500 total rushing yards and fumbled six times in 184 carries. Though Gordon still averaged less than 4.0 yards per carry this season (3.9), he gained 2.5 of them after contact (up from 2.2 as a rookie), scored 10 times and put the ball on the ground only twice, with 70 more carries (254).
Second-year player on defense
As a rookie, Collins played 56.0 percent of his snaps lined up deep in the secondary as a free safety, and it was ugly. But in his second season, he was there on 36.7 percent of his snaps, and he was used far more as a box weapon. His 46 defensive stops are eight more than the next-best safety, and he either picked off or broke up 10 passes.
Last season was something of an anomaly for Luck. He was playing poorly, then got hurt, then was badly injured before being shut down for the year. He had the best season of his career in 2016, with a PFF grade of 92.4, which is four points higher than his previous best in 2014.
Miami's season got on track when the Dolphins started riding Ajayi, becoming a power running team. Ajayi led all runners in average yards per carry after contact (3.5), more than Todd Gurley managed in total yard average. Ajayi broke 58 tackles as a runner -- 11 more than the next-best mark -- and did so despite being just ninth in carries.
Overall wide receiver
Cooper dropped 18 passes on 87 catchable targets last season. On the exact same number of catchable targets this season, he dropped only four. The rest of Cooper's numbers improved only marginally, but he displayed far better hands in his second season. He remains a dangerous weapon for the Raiders' passing attack, flashing much of the playmaking ability that helped make him the No. 4 overall pick in 2015.
Bakhtiari was already a good pass protector last season, but he was arguably the league's best in 2016. He allowed just 20 total pressures, despite pass blocking for a quarterback who held the ball on average longer than every other QB in the league after Tyrod Taylor. The Packers' investment in?Bakhtiari looks wise.
The return of longtime offensive line coach Dante Scarnecchia has done wonders for the New England line, and no player enjoyed a greater improvement than Cannon. The right tackle's PFF run-blocking grade jumped to 87.3 from 68.1, and the Patriots had nearly 500 more rushing yards than last season.
Shelton's rookie season in 2015 was far from great, recording mediocre grades and only 19 defensive stops. But this season, that number jumped to 39; only Damon Harrison?(49) had more.
As a rookie, Beasley had just 42 total pressures and four sacks. In year two, he finished the regular season with 56 total pressures and a league-leading 15.5 sacks. He had four multiple-sack games and recorded pressure in all 16 games.
Campbell has been a top-level interior presence for a while, but he really stepped up his pass rush in 2016, recording three more sacks, five additional pressures and three extra batted passes on fewer pass-rushing snaps than a year ago.
In 2016, Posluszny somehow became the linebacker he once was. Over the past four seasons, his average PFF grade has been 48.1, but this season, he finished with 88.4 and a spot on PFF's second team All-Pro team. He cut down his average receptions allowed from 11.1 a year ago to only 9.4 this season and allowed 74.1 percent of targets to be caught, down from 80.7 a year ago.
Peters had eight interceptions as a rookie last season, but he also allowed eight touchdowns and almost 1,000 receiving yards. He was a gambler who lost as often as he won. In 2016, he allowed only three scores and some 300 fewer yards, while still picking off six passes.
Runner-up:? Janoris Jenkins, New York Giants
It was a career year for Ryan, who had a league-high 136.1 quarterback rating on throws targeted 20-plus yards downfield. He was 32-of-63 on such throws, with three drops from his receivers. He was also the only quarterback to not throw a single interception on a deep ball in 2016. This comes after a season in which he threw more interceptions (five) than touchdowns (three) on deep balls.
Passer under pressure
Rodgers had 153 attempts under pressure this season, and he managed a ridiculous 12-to-1 touchdown-to-interception ratio on such passes. Fourteen other starting quarterbacks threw more interceptions than touchdowns when faced with pressure this season. Rodgers' passer rating under pressure jumped more than 20 points from 2015.
Runner-up:? Sam Bradford, Minnesota Vikings
Overall passing accuracy
After finishing 17th in 2015 with an adjusted completion percentage of 73.2, Tannehill made quite the leap to sixth overall (77.4 percent), before hurting his knee in December. It's not as if he was drastically changing the throws he was asked to make, either, in coach Adam Gase's offense; Tannehill's depth of target dropped only slightly, from 8.9 in 2015 to 8.2 this season.
Stafford's propensity to scramble didn't change much from 2015 to 2016, but his effectiveness certainly did. Last season, he had 26 runs past the line of scrimmage for 171 yards (6.6 yards per carry), while this season he scrambled 27 times for 213 yards (7.9 yards per carry). He also had four broken tackles, after only two in 2015.
Runner-up:?Tyrod Taylor, Buffalo Bills
Breaking tackles/extending runs
No starting running back was tougher to bring down this season than Ajayi. He led all backs with 58 broken tackle and 3.5 yards after contact per attempt. Both figures were tops by a good margin. His 75.5 elusive rating is the fifth best for a running back in the past 10 years.
Runner-up:? Isaiah Crowell, Cleveland Browns
Catching the ball out of the backfield
This one is easy. Johnson led all backs in receptions (80), yards (879) and broken tackles (27) in one of the most-impressive receiving years from a running back PFF has ever graded. He nearly doubled his output from a season ago in each of those categories. Even with the volume he had, Johnson still somehow ended up fourth in yards per reception (11.0).
In his final season with the Dolphins, Matthews saw just three catchable passes thrown his way on passes 20 yards or further downfield. He caught all three of them for 115 yards and two touchdowns. He saw 11 catchable deep passes thrown his way this season, catching them all for 388 yards to rank seventh in the league.
Beasley picked up 406 yards from the slot in 2015, averaging 1.15 yards per route run with two drops and five touchdowns. This season, his yardage rose to 647 yards, his yards per route run to 1.88 (the ninth-best mark in the league) and his drops stayed at two.
Graham's first season in Seattle was solid, if not up to the standards we had come to expect from his prolific time in New Orleans with Drew Brees. This season, highlighted by that incredible performance against Buffalo, when he had two touchdowns with defenders draped over him, his PFF grade rose from 80.6 to 85.0.
Despite his playmaking ability, Cooper gave the Raiders cause for concern as a rookie, dropping 18 of the 87 catchable passes thrown his way in 2015. After ranking second-to-last in drop rate in 2015, he finished 28th best in his second year in the league, dropping only four of the 87 catchable passes thrown his way.
In 2015, Gay allowed 0.84 yards per coverage snaps and a reception once every 10.5 coverage snaps from the slot. He allowed even fewer this season, giving up 0.61 yards per coverage snap, the second-best mark in the league next to Chris Harris Jr., and a reception just once every 10.9 coverage snaps from the slot.
Runner-up:? Nickell Robey-Coleman, Buffalo Bills
No player in the league made the improvement from his rookie season to his second year the way Collins did. His missed tackles dropped from 15 to 12, while his tackles resulting in a defensive stop climbed from 32 to 46, all of which contributed to his PFF rating rising from 58.0 to 92.1.
Runner-up:? Tony Jefferson, S, Arizona Cardinals