https://blogs.fangraphs.com/fangraphs-audio-eric-longenhagen-and-dan-szymborski-do-frisk-assessment/ Dan and Eric talked about Keston from about 43:30 to the end of the podcast. They mentioned that when he faces a fastball above 93mph (including MiLB), he whiffed 180 times and put the ball in play 126 times, roughly a 3 whiff to 2 BIP ratio. By comparison, Wander Franco has a 1 whiff to 3 BIP ratio. I'm really interested to see what he does on those sorts of pitches going forward. Essentially, can he tune back in to a big league fastball?