All the data suggests it has nothing to do with the pitch clock, but from "chasing velo."
I will say that the pitch clock might be a significant factor, since it stands to reason that: you're more likely to have injuries with bad mechanics, you're more likely to have your mechanics fall out of whack the more tired you are, and you're more tired with 18-24 seconds between pitches vs no clock.
But David Cone said the most apt thing ever over 20 years ago: Pitching is violence on your arm. Period. It's unavoidable for every pitcher to have damage. Nolan Ryan tore his UCL, he just did it on his last pitch in his 27th season.