Here are some guys to be concerned about heading into the 2009 season:
Clinton Portis - It's almost hard to believe Portis is just 28-years old because it seems like he has been around forever. Having joined the NFL at the age of 20, he is entering his eighth season, so he does have some wear on his tires for a guy his age. On top of that, Portis leads the league over the last two seasons combined with 642 carries and is coming off a season in which he toted the ball 342 times. That's not an unprecedented total, but is cause for some concern. If Portis is one of your starting backs, you better make sure you have a solid backup.
Thomas Jones - Although Jones is coming off one of his best seasons ever, age (31), a contract dispute, 600 carries over the last two seasons and a rookie in Shonn Greene looking to steal some carries make him a bit of a risky pick.
Jamal Lewis - I thought Lewis was washed up a couple years ago, but he proved to have more left in the tank than I thought. Lewis, who is now 30-years old, saw his yards-per-carry average drop in 2008 to 3.6, though, as he struggled to crack the 1,000-yard plateau, and he could be beginning to wear down after carrying the ball nearly 900 times over the last three years.
LaDainian Tomlinson - Years of consistently carrying the ball more than 300 times per season may finally be catching up to Tomlinson. L.T. has topped the mark in each of the last seven seasons. He struggled with injuries the past couple seasons, which could be a sign he is beginning to break down. And in 2008, he posted the lowest yard-per-carry average since his rookie season. He's probably got a couple solid seasons left in him, but his days as a fantasy stud may be over.