The hard-throwing Dominican right-hander signed with Toronto, a lesser-known 17-year-old given his lack of size and questions about his ability to start. He has continued to work in the rotation moving up the ladder, however, and has pitched his way to High A as a 21-year-old. I saw him just before his promotion, a late-May start for Lansing in the Midwest League.

In this look, Diaz was effective with a two-pitch mix, sprinkling in a few changeups for a third look. The fastball is his best pitch, sitting 92-to-93 mph (t96) with explosive late life up in the zone when he reached back for the second gear. He elevates his heater well, and the velocity and life combine for a future 55-grade offering despite what might always be fringy in-zone command. Diaz paired the heater with an 11-to-5 curveball that was inconsistent, but effective as a chase pitch. He’s less confident throwing it in the zone, and overall, while the biting action is above-average, his ability to locate it in or near the zone leads the pitch to play at average. His changeup is more of a show-me pitch, and it does not project beyond a 40 grade, which ultimately will prevent a starter’s role for Diaz.

As a two-pitch FB/CB reliever, Diaz’ fastball projects to play up a tick. The curve is still developing, and flashes the potential to be another above-average pitch in a leverage role, giving him a middle relief ceiling that he can reach in the next few seasons.