Hey trebeck, I feel your pain. I used to throw with a bit of an inverted W myself, fortunately I didn't suffer any injuries. One thing I did wrong in trying to fix my inverted w was trying to change my arm action and use connection balls to create muscle memory. I've learned since then that the inverted w is directly related to a lower half mechanical problem and that your arm is at the mercy of your hips. Look for a pitching coach who can help you refine your lower half mechanics and get your legs working the correct way. One drill I like to use is called showing the sole. When you step and throw, try to show the sole of your lead leg foot to the batter ( just slightly, not over exaggerated) as long as you can and then let that foot plant flat almost thinking toe first. Don't let your heel strike and then your toe, as this could be causing your problem. This will keep your lower half close and cause your hips to rotate much quicker and later and should keep your arm elbow from getting above your shoulder. Again, look for a coach who can help with your lower half, and once you fix any problems with that, your inverted w will more than likely fix itself.