Graterol gave up one run over 4.2 innings Friday in his debut for Double-A Pensacola. He struck out six, walked two, and twice reached 100 mph on the radar gun.
The 20-year old pitches comfortably in the high 90s and has become Minnesota's top pitching prospect. He'll need to improve his secondary pitches to dominate at higher levels, but his first Double-A outing was encouraging.