Things change so quickly in the NFL. Just two years ago, Peyton Manning was setting new NFL season records, throwing for 55 touchdowns and 5,477 yards. He won his fifth MVP award. Since then, his decline came rapidly and this year had his worst season, throwing 17 interceptions to just nine touchdowns, while missing seven games with plantar fasciitis.
Calvin Johnson was the most dominant receiver in football just a short while ago, but the last couple of years, nagging injuries have caused his numbers to dip and the culture of losing in Detroit has seemingly ended his career.
The point is, sometimes in the NFL, you just can't expect a player's contributions to last a long time. More players seem to be retiring at a younger age, either to walk away from the game while they're still healthy or a decline in production.
Marshawn Lynch was perhaps the best running back in football from 2012-2014, but injuries this season have suddenly put his career in question. Many feel he's done in Seattle and may even choose to retire.
The decline can happen very quickly. Great seasons can easily be an aberration in the NFL. Whether it be a player aging or having to adjust to a new system, players can have difficulty replicating the same kind of success they enjoyed just the year before. Things always go wrong in the NFL just when you think a player is on to better things.
Who knows, maybe Tom Brady will experience a quick decline soon. Maybe New England's lack of depth on the offensive line and the lack of a deep threat will cause Brady's numbers to slip. I wouldn't bet on that, but no player is immune to a steady, or even rapid drop in production. The 2016 season is a long time away, but from some patterns we've seen around the NFL, we can guess that these players may not be able to build on their 2015 success or even their entire career's success.
15 Charcandrick West
Charcandrick West took full advantage of the opportunity presented to him this year. After Jamaal Charles tore his ACL, many assumed the Chiefs' season was done, but West was able to help the Chiefs rebound from a 1-5 start to earn a playoff berth at 11-5. West was able to average 4.0 yards on 160 carries for 634 yards and four touchdowns. The Chiefs will have Charles back and West simply will not get the carries he got in 2015, barring another injury to Charles.
14 Arian Foster
Arian Foster has always had trouble staying healthy and his absence hurt the Texans' offense this past year. Having Foster back healthy is possible for Houston, but management and ownership have openly expressed frustration with Foster's constant injury woes. Coming off a torn Achilles at age 30 (come fall), it's unlikely Foster will replicate the kind of success he's had in the past. It's more likely the Texans cut him and he becomes a situational back elsewhere.
13 Ryan Fitzpatrick
Ryan Fitzpatrick has always seemed to be in that middle ground of great backup to mediocre to good NFL starter. The Jets took a chance on the veteran journeyman this year and he rewarded them with the best season of his career. The Jets went 10-6 while Fitz threw 31 touchdowns, but once again was prone to turnovers, throwing 15 interceptions. His performance in the season finale cost the Jets a playoff spot and it's unlikely the 33-year-old will replicate his 2015 season. The Jets have to look for a long-term solution at QB.
12 Kirk Cousins
No, I'm not here to say that Kirk Cousins' 2015 season was a complete fluke and he's never going to find any success in the NFL ever again. It's just that with plenty of film on him now going into 2016 and with expectations being far higher than 2015, it will be tough for Cousins to surprise people. Don't forget that Washington didn't beat any team with a winning record in 2015. Having won the NFC East, they'll now play a first-place schedule, which will be tough on Cousins and the offense.
11 Ted Ginn Jr.
Ted Ginn did what many thought he would never do; he was able to fill the role of a no.1 wideout, on an offense that scored more than anybody in 2015. People wrote off the Panthers when Kelvin Benjamin tore his ACL in training camp, but Ginn's 10 touchdowns and constant presence as a deep threat opened stuff up for Greg Olsen and others. With Benjamin coming back next year, Ginn will get less targets. While the Panthers will be an even better offense, Ginn's personal stats will suffer.
10 Gary Barnidge
When you all of a sudden break out as a tight end in your seventh season, odds are it's an anomaly rather than the norm. Gary Barnidge has basically been a blocking tight end throughout his career, but for whatever reason, enjoyed an amazing season from a personal standpoint, catching 79 passes for 1,043 yards and nine touchdowns. Those are elite numbers for a tight end, but it's incredibly hard seeing Barnidge repeat anything close to that in 2016 and going forward. If this is the new norm, he'll be one of the great late bloomers in NFL history.
9 Chris Johnson
The old CJ2K had an unceremonious ending to his career with the Tennessee Titans and after disappointing with the Jets, it seemed his career was done. He enjoyed a decent resurgence in Arizona this year, finding himself on a team with a good offensive line and a big threat in the passing game, opening up space for Chris Johnson to work with. He averaged 4.3 yards a carry before injuries ended his season. While it was a good short-term solution for the Cardinals, odds are they'll turn to David Johnson to carry the load going forward.
8 Matthew Stafford
While Matthew Stafford's 2015 season was a dip from his 2014 campaign in terms of his win-loss record, Stafford was still able to throw for a few more yards, increased his completion percentage to 67.2 and upped his touchdown passes from 22 to 32. The reason those numbers will take a hit in 2016 is the expected retirement of Calvin Johnson. Megatron has long made it easy for the Lions to find a big play, but with that threat eliminated, the numbers will dip.
7 Golden Tate
For the same reason just mentioned, Golden Tate might take a step back in 2016. He now finds himself as essentially Detroit's no.1 wideout when he was signed on to be the second option behind Megatron. His receiving yardage total already dropped by about 500 yards from 2014 to 2015 and unless the Lions bring in another big receiver to replace Calvin Johnson, Tate will be keyed on by opposing defenses and will find it tough to put up big numbers.
6 Julius Peppers
All Julius Peppers does is find the quarterback and sack him. Even in his mid 30s, Peppers was still able to register 10.5 sacks in 2015. His place on this list can't really be justified other than the fact that he's now 36 and has played on the defensive line for many years. There are rumblings that the Packers could release Peppers to find a younger, cheaper replacement and if that's the case, it could be tough for him to find a place where he can be comfortable.
5 Demaryius Thomas
Demaryius Thomas signed a big contract extension with the Broncos prior to this season. While he didn't have a bad season, the Broncos' offensive philosophy has changed drastically since Gary Kubiak's arrival. The team is now built on having a strong running game and shutdown defense. All signs point to Brock Osweiler starting for the Broncos next year, as Peyton Manning is expected to retire. With Osweiler as his quarterback, Thomas had 44 catches over the course of about half a season, well below his usual pace. Thomas' presence will still be valuable to Denver, but with a run-heavy offense, his numbers won't match years past.
4 Steve Smith
2015 was supposed to be Steve Smith's last season, but after his season ended thanks to an Achilles injury, Smith decided to come back for 2016, not wanting his career to end that way. With the Ravens having had such a difficult 2015 season, it will be tough for them to rebound in 2016 and will be even tougher for Smith. He has always found a way to be productive in his career, but at 37 years old by fall coming off a torn Achilles tendon, it's hard to see him getting a storybook ending to his career.
3 Carson Palmer
Carson Palmer looked really good in 2014 and looked even better this past season, despite coming off a torn ACL. At 36 years old, Palmer had the best season of his career, throwing for 4,671 yards, 35 touchdowns and 11 interceptions. His season ended in a trainwreck of a performance in the NFC championship, in which he threw four interceptions after thowing two the previous week against Green Bay. Whether the ending of his season was a short term slump or signs of a decline won't be known until later this year.
2 Tony Romo
We have to look at this last season as a write off for Tony Romo. While many were expecting him not to top his numbers from 2014, nobody expected Romo to miss most of the season with two collarbone injuries. Coming back in 2016 on the wrong side of 35 will be a tall task for Romo and the Cowboys. We've now seen just how much Romo means to the Cowboys' chances at contention and it's tough to see Romo being as effective going forward.
1 Adrian Peterson
Adrian Peterson rebounded beautifully after a full year off from football in 2014, due to his indefinite suspension from the NFL. He led the league in rushing with over 1,400 yards at 30 years old. His return was a big reason the Vikings were able to win the NFC North, but with the Vikings transitioning to being Teddy Bridgewater's team, Peterson may not be the focal point of their offense next season. This is a simple estimation of running backs declining in the NFL and Peterson has run an awful lot. Peterson set the bar high in 2015, so it'll be tough for him to live up to that in 2016.