Signed for just $10K out of Tennessee Wesleyan in 2016, Hartman’s climb through the Astros’ system has exceeded initial expectations. He put up arguably the best stat line of any pitcher in the Texas League this year, posting a 2.69 ERA with a 30-percent strikeout rate and 1.94 BB/9 in 120.1 innings pitched.
Hartman pounds the zone from a low-effort semi-windup. His fastball hovers around 90 mph, able to go upstairs for swinging strikes despite limited velocity due to its quality spin and ride. He mixes a short cutter for another look, commanding both fastballs effectively to different parts of the zone. Hartman’s primary off-speed is a fringy curve with sweepy slant across the zone, though it’s played up a bit by his ability to land it. He can establish his fastball enough that he won’t show a third pitch as much as you’d expect from a finesse lefty. A mid-80s changeup plays as a 45-grade pitch, showing occasional tumble but straightening out at times.
He doesn’t have overpowering stuff, but Hartman’s mix of control and pitchability will get him to the big leagues. His success in Double-A this year isn’t a mirage, though he lacks a carry pitch for a regular rotation role. A realistic ceiling is a swingman at the Major League level, a better fit to pitch in a long relief role but able to spot-start if needed.