Let me preface this: I’m biased. I absolutely LOVE Luis Castillo. His ceiling is near-unmatched in the MLB. He’s got 4 pitches that have plus-to-plus plus upside, elite velo, and age on his side. That being said, he’s been truly atrocious so far in 2018. Allow me to dive into the numbers and graphs and play a little bit of doctor!
You may know me as the guy that does the dScore evaluations of players. While I haven’t done any so far this year, I’ve kept up with the analysis on my Google Doc and I’ll probably release one closer to the All-Star Break. One thing that I’ve noticed is, despite the putrid surface-level numbers (5.64 ERA, 1.45 WHIP) Castillo has consistently scored well on my metric. Not as well as last year when he was a certified stud, but he’s floated around the lower end of the #2 breakpoint (20+ points). This tells me that, purely based on his stuff, he’s getting pretty royally unlucky – or that something else is wonky. There’s been documented evidence that his velo is down from last year and that he had an issue getting his arm slot dialed in. His last month has been measurably better, showing regression towards last year’s outcomes (K% up from 18% to 25%, BB% down from 10% to 8%, BABIP normalized from .330 to .290). The two things that haven’t regressed are pretty key to this analysis: his hard contact has stayed abnormally high (38%) and he’s continuing to not generate ground balls at near the rate he was last year (45% vs 58%).
Here’s where the fun begins.
Source: Luis Castillo: A Study in Sophomore Slumps | Community – FanGraphs Baseball