Many things can go wrong with NFL players. Injuries happen, skills regress and mechanical flaws develop. Other times, players need a simple confidence boost.
It's easy to spot players in need of a confidence boost. They are typically talented and often have a history of success, but they simply aren't playing as well as they can.
This applies to every one of these players. Confidence may not be the only issue with them right now, but it is a significant one.
Josh Freeman has proven he can play quarterback. In 2010, he excelled, throwing 25 touchdowns with a 95.9 quarterback rating. The past two seasons haven't gone as well, as he has put together just a 78.1 rating combined.
Freeman's arm is one of the game's stronger ones, and he has an excellent combination of size and athleticism. Something has gone amiss since his breakout 2010 campaign, though.
Perhaps Freeman had a fluke season that year and will never again be that good. Or maybe he just got into a bit of a rut and lost the confidence that helped him succeed.
For several years, Philip Rivers was among the NFL's best quarterbacks. From 2008 through 2010, he had 103.8 quarterback rating. Then, in 2011 and 2012, his numbers plummeted.
Over the past two seasons, Rivers' quarterback rating was just 88.7. That's a huge drop, and there is no obvious reason for it. Rivers' supporting cast isn't quite what it used to be, but his play simply hasn't been as sharp.
Rivers is 31 years old, so he shouldn't yet be declining like this. It would serve him well to remember how good he can be.
In his rookie season, Trent Richardson struggled with injuries, but they were far from the only thing negatively affecting his play. Far too often, Richardson hesitated in the backfield, as if he were unsure where to run.
This could be attributed to a lack of vision, but Richardson showed at Alabama that wasn't an issue for him. This was a confidence thing. Maybe his injuries destroyed his confidence, but no matter what the cause, it wasn't there.
In 2013, Richardson has to stay healthy. But he also needs to find the confidence to burst through a hole without a second thought, or he will never be a premier running back.
A superbly talented safety, Eric Berry almost had his career derailed by a torn ACL in 2011. He missed nearly the entire season, and in 2012, he wasn't the same player.
This happens to many players coming back from severe injuries. They aren't yet confident in their recovering body part and don't move like they used to. This was clearly the case for Berry, who hesitated too often and didn't play with the same ferocity.
By the end of 2012, Berry had started to come around a bit, but he still wasn't the ball-hawking safety he used to be. Hopefully, in 2013, Berry will have regained full confidence in his knee. Otherwise, he may be doomed for a career of mediocrity.
28-year-old kickers don't suddenly forget how to kick. In 2011, Mason Crosby made 85.7 percent of his field-goal attempts. In 2012, his percentage dropped to 63.6. He made just two of his nine attempts over 50 yards.
Because he is still young, this isn't an issue of physical deterioration. Crosby didn't lose his leg strength. He lost his confidence. For a kicker, confidence is everything.
If a kicker doesn't believe he will make a field goal, he won't. It is a position with extreme pressure, and a kicker who lacks confidence won't survive.
With another year like Crosby's last one, it could be his last season.