I'll make it quick, because there's only so much you can say about a 157 pitch sample over 4 appearances. Over 10 2/3 innings, Moseley has allowed 4 walks and has struck out 5, which are unimpressive numbers. He had a 2.2 BB/9 in 12 starts at Scranton this year, so I wonder if the walks will start returning to his minor league levels or if facing major league hitters will hurt his control. Early on, Moseley has a spectacular .625 ground ball rate, which matches up nicely with his .594 mark in the minors. Moseley's repertoire features a two-seam fastball (a bit less than 50% of the time), a cutter, a curveball, a changeup, and maybe a few four-seam fastballs. Over his four games, the fastball has averaged 89-90 mph, the cutter around 86, the change 83-84, and the curve 78. He fits a similar bill as Mitre as a ground-ball specialist with solid control; the Yankees are certainly hoping that he can perform better than Mitre has in the rotation.
Gameday data is from MLB Advanced Media; it can be easily accessed through Joe Lefkowitz's invaluable tool.