Angel Castro is a pitcher that has been pitching in the Dominican winter league. He throws 95-96 MPH (he went up to 97 according to one radar gun in the Dominican Republic). In the Dominican he had a 1.86 GB/FB rate with a 2.53 ERA. Overall, he has a pretty impressive -2.73 PE with a .253 OBP against. This projects to a .287 OBP against in the Majors, which is pretty dominant.
He spent 2011 in the Mexican League and gave up an ERA of 5.45 despite having a 3.00 GB/FB and 7.7 K/9IP. He gave up an amazingly bad 12 H/9IP and a WHIP over 1.8. He suffered from a .389 BABIP that one can deduce is from a bad defense, since he gave up 6 unearned runs as well, and his FIP was 3.88. He did keep the ball in the ballpark with a .5 HR/9IP rate.
AA is where Castro had problems, as he had a 4.48 ERA in 64.1 innings, with a 1.477 WHIP and 6.2 K/9IP. Most of the problems stemmed from his 18 inning stint with the Phillies organization, where he had a 49.7 LOB% and .369 BABIP. His stint with the Tigers in AA wasn't that bad with a 3.96 FIP. This still isn't very good and projects to a ERA of around 5.40.
After watching Castro throw a few times in the Dominican this off-season, I don't have much doubt that he can pitch in the big leagues. It would be a real shame if he has to go back to the Mexican League to pitch.