In the sports world, the debate on whether a player is overrated or underrated is a very tricky subject. Is a player like Tim Tebow underrated because he has so many critics or overrated because of all the media hype? Over or underrating someone is based solely on a person's perception of that player. A player is usually overrated if the majority of the fanbase thinks they are better than they actually are.
Sam Bradford is a good example. He put up good numbers for a rookie quarterback last season, but he never really rose to the occasion in a big game. He is a nice quarterback, but he probably will never be in the discussion as a top 10 quarterback. However, he was deemed a great pick early in his rookie season. Now that the Rams offense is really struggling due to a poor offensive line and no dangerous skill players, you could now make the argument that he is underrated.
In the Philadelphia Eagles' 79 years of pro football, they have had hundreds of players you could characterize as being either under or overrated. A guy like Freddie Mitchell who really had one good catch in his entire career but still got a lot of hype and air time was way overrated, while a guy like Al Wistert is an unknown to a very high majority of Eagles fans even though he was one of the best they ever had.