Tyler Pastornicky was listed as a possible breakout / sleeper by John Sickels on minorleagueball.com Pastornicky was the 5th round pick of the Toronto Blue Jays in 2008 and after having a solid Gulf Coast League season, he is being tabbed as a player to watch. A sample from the linked article.
There are two basic types of "breakouts." The first types are guys who are already in the consciousness of the prospect community, but who are still unproven or at a low level of play. These would be guys rated as Grade C+ or C types at lower levels, but with the potential to improve. The second type is the guy who REALLY comes out of nowhere, or who makes a dramatic, unexpected, or unpredictable improvement from year to year.
Tyler Pastornicky, SS, Toronto Blue Jays: A deep sleeper type, Pastornicky was a fifth round pick out of high school in Florida last year. He hit .263/.349/.356 in rookie ball, showing decent plate discipline but lacking power. However, he kept his strikeout rate low, stole 27 bases in 32 attempts, and has a good defensive reputation. He's young, athletic, and commands the strike zone, qualities inherent in prospects who can sneak up on us. Power development will be his key.
Pastornicky was an outstanding high school player at The IMG Academy School who spent 4 years at the IMG Academy baseball program. A Florida State commit, Tyler decided to sign with the Blue Jays after being selected in the 5th round. During the offseason, Pastornicky trained at the Athletic & Personal Development program in preparation for his first full season of professional baseball. The 6' 175 lb shortstop gained 15 lbs during the offseason while managing to lower his 60 yd time to a 6.58.