It was a poised and confident Double-A debut for Keller last week in Trenton, as he threw 6 innings of five-hit ball, allowing two earned runs, walking three and striking out five.
Keller, taken in the second round of the 2014 draft out of Xavier H.S (Cedar Rapids, IA), is one of the best arms in the Pirates’ system, and he showed solid, repeatable mechanics built from a base of strength in his lower half, with a long, fluid arm action that generates easy velo through a ¾’s slot. The consistency of the delivery shows in his plus control numbers (2.4 BB/9 in his brief career, and 2.3 BB/9 equally spread across three levels this season).
He showed a real presence on the mound and using his fastball aggressively as an effective two-way offering. The two-seamer showed the most movement, thrown in the 93-to-95 mph range with plus tailing action, and the four-seamer was a real beast in the 94-to-96 velo band – reaching back for 97-to-98 mph on occasion – with bore and late life on some, and some heavier cut action on others, and showing plus movement. He was able to spot the pitch to all quadrants with above-average command, and even showed some effective wildness to keep hitters honest. While most readings were in the 60-to-65 grade range, the movement and variance play it up to a 70-grade, double-plus offering.
His best secondary is his plus 11-to-5 curveball, which has depth and sharp biting action at 78-to-82 mph. He showed good feel both to vary the break and throw it for strikes, and get plenty of swing and miss as an out-pitch. The fastball-curveball combo was effective enough to virtually eliminate the need for the changeup in this view, though he did throw a couple in the 78-to-79 mph range as he worked his way through the lineup a third time. It’s not a stretch to see the offering become an average secondary with increased use, given the arm action and the polished mechanics he possesses.
Still just 21 years old and moving quickly through the system, Keller is giving up just 6.7 H/9 this year in his 93 1/3 innings while striking out 8.1 per nine, and his GO:AO rate has jumped to 1.66 this year from 1.07 in 2016. He could still see a tick or two of added velocity as the body matures, which would be a real sight to see if the added upper-body strength comes. It’s an impressive overall package, and the combination of velocity, movement and control of the arsenal is something to dream on. He has a moderate-risk ceiling of a Role 70, number two starter who will flash signs of a true number one when he is on.