The Marlins signed German as a 17 year old from Pedro de Macoris in the Dominican Republic during the 2009-10 international signing period for just 40 thousand. German would then spend next four seasons in the Marlins organization before being traded to the Yankees in the Martin Prado trade.
German developed very slowly in his four seasons as a Marlin. He spent his first two seasons in the Dominican Summer League (DSL). German pitched very well there, but mostly out of the pen. In his two seasons in the DSL German posted a 2.89 ERA, a 3.08 FIP, and a 1.38 WHIP. He struck 83 batters in 81 innings, while walking 40.
German came stateside in 2012, and had an up-and-down first season in the Gulf Coast League (GCL). In his first season in the Gulf Coast League German put up the following numbers: 1.61 ERA, 2.99 FIP, 1.48 WHIP, an 11.69 k/9, and a 6.45 BB/9. All of his innings came in relief, and as you can see he really needed to fix his walk-rate.
In from 2013 on his walk rate improved dramatically, and he really started putting up the type of numbers you’d expect to see from a top pitching prospect. He repeated the GCL level in 2013, and posted the following stats: a 1.38 ERA, a 2.69 FIP, a .77 WHIP, a 9.35 k/9, and a BB/9 of 1.73. His impressive performance led to a promotion to the NYPL, where he continued to show improved control (BB/9 of 1.10), and an overall dominating stat line. In 41 innings at the level he posted an ERA of 1.76, a FIP of 2.10, a WHIP of .93, and a k/9 of 7.46.
Overall 2013 was a very big year for German, but it was his 2014 season that garnered national attention. He spent the entire 2014 season in A-ball, and pitched 123.1 innings. In those innings he posted the following numbers: a 2.48 ERA, a 3.26 FIP, a 1.14 WHIP, an 8.25 k/9, a BB/9 of 1.82. Additionally he appeared in the 2014 future game, and impressed many by striking top-prospects Joey Gallo, and Kris Bryant.
His overall performance resulted in Baseball America ranking him as the 16th best prospect in the Sally league (just one spot below Ian Clarkin), and as the Marlins 6th best prospect. The Yankees system was considered deeper than the Marlins so he was ranked a bit lower as a Yankees prospect, but overall most pundits thought he was a top-10 Yankees prospect.
Obviously he is no longer regarded as such, and that’s purely because he missed the year due to Tommy John surgery (TJS). German was slated to begin the year in A+, and he had a lot to work on at that level. German has a plus fastball (92-97 MPH), and an average change, but needed to work on his command and his curveball in order to be considered a true starting pitcher. Now that he is due to lose more than a year of development time it’s unclear if his future is still in the rotation.
German will most probably begin his season in A+, and if he is a starter he will probably need to stay there for the full season. German’s future is unclear, but if he is able to improve his curve, there’s no reason to think he can’t be a good mid-rotation starter.