"Looks to me like Clemens hip rotation takes him past square. At least from the photo in your report."
It does, but not too much. There are other hard throwers who still finished up square to the plate.
"And your Maddux report doesn't show how he ends up after landing."
I'm trying to find more complete pictures. In the meantime, check out bbscout's (great) clip of Greg Maddux...
- Greg Maddux Clip
"Pulling the glove back behind the body does entail a little longer reaction time to the combacker. But it does accomplish two important things. Clearing the glove side shoulder dramatically reduces stress on the throwing arm during deceleration. And by allowing the arm more time until the onset of deceleration, the arm velocity is greater through the period of release. A tradeoff, but a worthwhile one."
I do agree that the longer deceleration path of the arm, the better.
However, the success of many successful major leaguers makes it clear that you don't have to finish with your glove-side arm behind your body to prevent injuries to the rear part of the rotator cuff. Given that, I recommend that pitchers finish in a strong fielding position, as long as doing so doesn't cause them to abbreviate the deceleration path of the arm.