Most overrated players are probably some Canadian players who were picked 1st overall and had a press following from their mid-teens, but then never hit that next-level status in the big leagues. I'm thinking guys like Marc-André Fleury, John Tavares, Steven Stamkos, or Vinny Lecavalier.
.. Huh? Which level was he supposed to hit? Stamkos has more Top-5 goalscoring finishes than Brett Hull and would probably have 6 straight Top-2 goalscoring finishes without his pretty gruesome injury, something Hull himself never came very close to achieve. While Hull probably has an overall edge due to peak, prime longevity (I'm taking for granted that Stamkos is post-prime, which may be a mistake), longevity per se and playoffs, they can't be THAT far from each other... And I don't think Stamkos was projected to be better than Brett Hull.
EDIT : Even as it is, Stamkos has four straight Top-2 goalscoring finishes. On top of my head, only Gretzky, Bossy, Ovechkin, Lafleur, Esposito, Richard and Howe achieved this, the last three in completely different contexts.