I have read the available literature. There isn’t a lot because coaches who have been teaching problematic mechanics for years aren’t really accept that maybe they are wrong.

But Ohtani flaw is that his arm is level with shoulder when he puts his lead foot down. This means his arm(read elbow) and shoulder are coming under load earlier than they should be. If you look at durable pitchers, even modern ones like Halladay and Verlander, their arms are up at foot plant(elbow above or equal to shoulder) this means that their arms are coming under load at the right time. Flat arms also break the kinetic chain and add superfluous movement on the arm and elbow.

Other pitchers like Mark Prior,Jarrod Parker or Matt Harvey who had these flaws struggled to be healthy. Why is Ohtani any different?

Try it yourself. You can feel the difference in your arm when you throw with bad mechanics like flat arm or the TJ twist.

You don’t need a P.HD in human kinetics to understand the flaws.