The co-centerpiece (along with Carlos Gomez) of the Johan Santana package, Guerra was rushed like a lot of Mets prospects are, and spent 2007 in the Florida State League at age 18. Wisely, the Twins kept him at that level this year, sending him to Fort Myers. How is he doing?
Guerra has pitched 63.1 innings for Fort Myers over 13 games, 12 starts. He has a 34/30 K/BB ratio, with 66 hits allowed. His GO/AO ratio is 0.62. There are all kinds of problems here, starting with the combination of a low strikeout rate and a strong fly ball tendency. That, frankly, is a terrible marker. Somehow he is 7-2 in the W/L column, but that's not meaningful when analyzing his future projection.
Everything I"ve heard indicates that Guerra has not been overly impressive, and the numbers back this up. He's throwing his fastball in the 80s most of the time and his secondary stuff is very erratic. Kiley McDaniel at Saberscouting has a pair of scouting reports about Guerra dating from May and April which discuss Guerra in detail. Basically you can see his raw talent and projection, but raw is still very much the operative word here.
Sabermetrically, I don't like the fact that his numbers have slipped compared to last year at the same level. His strikeout rate and walk rate have both deteriorated, and that's never a good sign when repeating a league, no matter how young you are. That said, Guerra is still just 19, and 2007 would have been his draft year. He would have been a first round pick out of high school last spring, and everything needs to be looked at through that scope. I gave him a Grade B+ based on his projection and potential in the book, and I won't change that now. But I do think we need to see some improvement in his component ratios as the season progresses. If he is still pitching like this by the end of the year, a downgrade will be needed.