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Selected in the 21st round of the 2009 draft, Rosenthal made impressive strides this year at Double-A Springfield in his second full professional season. A starter in the minors, the 22-year-old right-hander was called up in mid-July and used out of the bullpen.
The debate is whether he has a brighter future as a starter or reliever. Rosenthal boasts a fastball that sits in the upper 90s—he hit 100 mph seven different times during his inning of work in Game 5—as well as a sharp, downer curveball and changeup, though he’s rarely thrown the last as a reliever.
As a starter, his fastball sits consistently in the mid-90s, as he throws more heavy two-seamers and cutters than four-seam fastballs. In 20 starts this season between Double-A and Triple-A, Rosenthal posted a 2.97 ERA, 6.4 H/9, 8.6 K/9 and 3.5 BB/9.
Appearing in three Division Series games, he was absolutely lights-out in each appearance, allowing one hit with six strikeouts over three and one-third innings.