A question that remains unanswered by Chris or his followers is how many pitchers have been injured after using non-inverted W, or M, mechanics. I’d be willing to guess that the number is enormous as compared to the inverted W.
Broken record time here. I’ve suggested over and over that this is, plain and simple, a nasty thing to ask your body to do. A very high risk activity. You’re taking the involved muscles and connective tissues to the extremes of what they can handle, regardless of the mechanics involved.
I also theorize, but admit to no statistical data supporting it, that along with over-use, velocity is a contributor to the magnitude of the injury risk. A well conditioned adult throwing slowly will have less injury risk than that same athlete throwing over 100 mph.
In a nutshell, throwing hard is tough on the tissues involved and pushing that to the extremes of what’s possible pushes you into the red zone farther and farther. I’d be curious to see what the stats would show if one were to track them.