Still building his pro resume after Tommy John surgery following his 24th-round selection in the 2012 MLB Draft, Mesa is starting to stretch out beyond two-to-three inning relief outings, hitting high-70’s pitch counts for the first time as a starter since his promotion to Trenton July 31 after compiling just 51 1/3 full-season innings out of the bullpen prior to his promotion.
Mesa works downhill from third base side of the rubber and generates good angle to make him a tough look out of his high ¾’s slot. The arm action is free and easy, and he works with moderate-effort mechanics and average arm speed. His upright finish allows him to really drive the ball down in the zone, and he repeats well for a big guy, making him tough to barrel up. He’s limited hitters to a .132 BAA in 34 1/3 Double-A innings, and sporting a 10.8 SO/9 rate.
His heavy fastball was at 90-to-93 mph and sitting mostly 92 mph, and the angle and downhill plane play it up to an above-average pitch. It’s at it’s best when he’s working in the lower half with mild run and tail, where it’s tough to get the barrel under it. His command was inconsistent in my two views, and he’ll get hit when he misses his spot and the pitch flattens on him, though the damage has been kept in the park (0.61 GO:AO rate, but just four home runs allowed in 84 innings this year).
The curveball was fringy, with 11-to-5 shape, loopy break and limited snap at 74-to-76 mph, though he showed the confidence to drop it in for some first-pitch strikes. The slider was also fringy in the 82-to-85 mph range, coming in short with more sweeping action than bite. Both project to average as he gains more feel for them. His changeup was average and it had tumble at 82-to-84 mph to generate some swing-and-miss.
His control numbers have dropped to a tolerable 3.4 BB/9 this year from a gaudy 6.4 BB/9 in 42 innings last year, and that could wind up closer to an average number as he stretches out his innings. He’ll also need to monitor his weight, as his XL frame has some natural thickness to it, but it lacks some definition at present. Mesa will have a chance to advance quickly in 2018 if he can prove his durability. He has a moderate-risk ceiling of a Role 50 number five starter if his BB/9 rate polishes up with experience. His realistic role, however, is that of a solid Role 40 swingman/middle reliever, where the present control numbers are survivable, and the stuff could play up in shorter stints.