Not everyone can be successful every year.
When predicting which NFL players could be in for a down year, several factors must come into play. Sometimes it's a player who took advantage of favorable circumstances to enjoy a breakout year; those circumstances may not be the same every season.
Other times, an individual goes from great surroundings to a less-than-perfect setting that might not allow him to be as productive.
A player can even be subject to a reality check when he plays "over his head" for a while—meaning he performs so well that he couldn't possibly keep it up forever.
Whether it's any of those situations, a combination of them all or something completely different altogether, any number of players will be given a harsh dose of reality this season. These ones need to watch out for a potential step back in 2014.