Hearn is opening the year in the rotation at Double-A Altoona, MLB.com's Jonathan Mayo reports.
He has some flaws, but 6-foot-5 lefties with upper-90s fastballs are tough to find, so Hearn should have no problem reaching the big leagues in some capacity. The 23-year-old notched a 3.41 FIP in 87.1 innings at High-A last season. If he can improve his command and his breaking ball, there's a chance he could be an effectively wild starter, but the most likely scenario is that he ends up as a high-leverage reliever, as his fastball would regularly hit triple-digits out of the bullpen.