It's not a 5 mph drop, because he rarely throws 4-seam fastballs (maybe he should!) very few of his pitches have been classified as such, and it's entirely possible a bad cutter just happened to end up registering at 87 or something. His actual velo drop is ~92 in 2017 down to 90 in 2018 and 2019 with the sinker, and 90 in 2017 down to 89 in 2018 and slightly below that this year on his cutter. So we're looking at more of a ~2 mph drop, which is still significant but unchanged from last season where he had success.