Every year, there are players who seem to come out of nowhere to post monster years. Whether they're prospects who realize their potential or relatively unknown players who just "find it" for a season, there are always a few.
It's hard to argue against Jose Bautista being 2010's AL Breakout star. After 2038 PAs of mediocre .238/.329/.400 hitting, Bautista crushed 54 home runs and led his league in total bases in 2010.
In the NL, the total bases leader was also a surprise breakout star: Carlos Gonzalez. Say what you will about his home/away splits, but Gonzalez smashed all expectations en route to a .336/.376/.598 year (oh, and 26 stolen bases just as a bonus).
I'd be interested to hear who TC's posters think the 2011 Breakout candidates are (putting it on a tee here for any of you who want to name a certain J.H.).