What constitutes a draft bust?

Everyone has a different opinion, but for me a 1st round bust is:

1. A player that doesn't make significant contributions to the team by the 3rd year.
2. A player that doesn't crack the starting lineup within 2 years.
3. A player that is injuried waaaaaaaaay too often.

Note: Exceptions of course can be made for unusual circumstances. For instance, I would not classify Aaron Rodgers as a bust yet.