Whether it's switching teams, losing teammates, injuries or just getting old, every year some well-known NFL players take a step back.
That's not even counting players who were one-year wonders.
It's tough to follow up record-setting seasons. It's also difficult to keep performing at a high level year after year. Sometimes it takes a while to adjust to a different offense or a new coaching staff.
Whatever the reason, decline is inevitable.
Some players whose stats might trend downward in 2015:
DeMarco Murray, RB, Eagles: Murray began last season with eight straight 100-yard games, breaking Hall of Famer Jim Brown's 56-year-old NFL record of six. He finished the season with 1,845 yards rushing, breaking Emmitt Smith's single-season Cowboys franchise record. But Murray left Dallas for a better deal in free agency from the Eagles. He won't get the same workload in Chip Kelly's offense. The Eagles also signed Ryan Mathews to help replace LeSean McCoy and they still have Darren Sproles. Kelly considers his backs interchangeable so he'll rotate them in and keep them fresh. Murray's $42 million contract means he'll get a bulk of the carries, but he shouldn't come close to the 436 rushes he had last year and it'll be tougher for him to match his 61 catches and 13 TDs.
Julius Thomas, TE, Jaguars: Thomas caught 24 TDs the last two seasons in Denver despite missing five games. He turned that into a $46 million free-agent deal from Jacksonville. But Thomas already is injured and will miss the first month because of a broken finger. When he returns, he'll have a tough time matching his production with the Broncos. Now he's catching passes from Blake Bortles instead of Peyton Manning.
Jeremy Maclin, WR, Chiefs: Maclin returned after missing 2013 because of an ACL injury and had a career year for the Eagles in 2014 with 85 receptions for 1,318 yards and 10 TDs. But Kelly's up-tempo offense helps players produces big numbers. Nick Foles, McCoy, Maclin and DeSean Jackson each had their best seasons playing for Kelly and none are still with the Eagles. Maclin got a $55 million free-agent deal from his old coach Andy Reid in Kansas City, joining a team that had zero TD catches from wide receivers last year. Maclin is the main man on the Chiefs, but it'll be difficult for him to match his performance in Philadelphia.
Peyton Manning, QB, Broncos: Manning is 39 and can't keep going forever. His TDs dropped from 55 in 2013 to 39 last year. He had six TDs and six interceptions over the last six games, including a playoff loss to Indianapolis. He's a 14-time Pro Bowl pick, seven-time All-Pro, five-time NFL MVP and will still outperform most QBs, but expect Manning's numbers to continue sliding.
Colin Kaepernick, QB, 49ers: Kaepernick appeared on the verge of stardom after leading San Francisco to the Super Bowl and conference championship game in consecutive seasons, but the team struggled in 2014 and doesn't have high expectations this season. The 49ers have a new coaching staff and Kaepernick will play behind largely a new line after taking 52 sacks a year ago. He spent part of his offseason working with Kurt Warner on his passing. Kaepernick may still become a superstar, but he may have more growing pains this year.
Justin Forsett, RB, Ravens: Forsett had a breakout year after replacing Ray Rice in Baltimore. He ran for 1,266 yards and eight TDs while leading the league with an average of 5.4 yards per carry. The Ravens rewarded with him a $9 million, three-year deal. But Forsett, who turns 30 next month, might be hard-pressed to do it again under a new offensive coordinator now that Gary Kubiak and his zone-blocking run scheme are in Denver.
Tony Romo, QB, Cowboys: Romo bounced back from back surgery and had an excellent year. He threw 34 TD passes and led the league with a 113.2 passer rating. But Murray's departure will impact the passing attack because defenses now can focus on shutting down Romo and forcing Dallas to run the ball.