It isn't the pitch clock. The answer for the rash of MLB pitching injuries is obvious for all to see.
We like sports because we like watching people do things that we cannot do. We can’t do those things because our bodies did not evolve to do them. Back before market forces intervened, sports were the domain of physical outliers, a playground for those in the upper percentiles of natural speed and natural strength and natural hand-eye coordination. Now, sports are a domain where those outliers compete to accrue extreme amounts of resources, i.e. money.
The important thing to keep in mind is the behavior of a pitch that is thrown with an entirely natural motion. More or less, a straight line. Go outside and throw an acorn at a squirrel. You will notice a ballistic trajectory, moving in direct path. The harder you throw, the less guesswork you leave to gravity, and the less time the squirrel has to react. Do it 100 times, and tell me how your arm feels. Now, pretend that squirrel has a bat, and he is trying to hit your acorn.
No. 4 on the list is Hunter Greene, who missed much of last season with a hip injury. No. 6 is Tyler Glasnow, who had Tommy John elbow surgery in August 2021. No. 7 is Brandon Woodruff, out for the season after shoulder surgery. Also ranking in the top 20: Verlander, Pivetta, Carlos Rodón, Alcantara, and Ohtani. All have missed significant time with injuries over the last three years.