The former third-rounder has been nothing shy of dominant in his return to Double-A Jackson after suffering through some growing pains in his upper-minors debut last summer. In his most recent start against Birmingham, in which he squared off against fellow power-righty White Sox Carson Fulmer (RHP, Double-A Birmingham), Diaz left a 94 mph fastball out over the plate to Adam Engel (OF, Double-A Birmingham) and had it deposited over the big wall in left. Eddy Alvarez (SS, Double-A Birmingham) followed-up with a hard double to the left-center gap off another fastball up and over the plate.
Those were the only two hits Diaz would allow, as the high wasted righty fanned the next two batters with a lively fastball at the letters and power breaking ball buried on the hands of Nicky Delmonico (1B, Double-A Birmingham) and closed out the inning drawing a 4-3 groundout on a changeup down and away from Trey Michalczewski (3B, Double-A Birmingham). The only opposing hitter to reach base over the next four innings would be Engel, who drew a seven-pitch walk in the third, as Diaz finished the outing with eight strikeouts, one walk, two hits and one run over five innings of work.
Notwithstanding the first two batters of the game, he was in control throughout, working primarily off his fastball and breaking ball while mixing in the changeup for flavor. On the season, Diaz currently sports 24 Ks against just two walks and has allowed just eight hits over his 16 IP. The Puerto Rican native has begun to fill out physically over the past two seasons and should continue to add strength as his body matures.
Most importantly, Diaz is showing a much more advanced approach in 2016, working his fastball in and out, and elevating the pitch when ahead in count. His slider is an impressive swing-and-miss weapon thanks to hard bite and a release and trajectory that dovetail well off his heater. He’ll need to continue to grow his changeup, but the early looks this year have the young righty projecting as a potential mid-rotation arm with a fallback as a potentially dominant late-inning reliever. –Nick J. Faleris