It's sort of funny that when he was drafted by the Giants, many teams were questioning his mechanics. He was viewed as an arm injury witing to happen. Now that he has a year an a half (or so) of MLB experience; he is viewed as "the Freak". FWIW I didn't read the SI article, but I heard that it actually goes as far as to praise his mechanics. It looks like a lot of his power comes from his long stride. His wind up is looks more lower body and less arm. doesn't matter where his power comes from, the transfer of kinetic energy from legs to arm still puts a tremendous amount of strain on the shoulder and elbow. you're not saving any strain on your ligaments and rotator cuff by using your legs more than your arm, you're just saving strain on your muscles. besides, in order to throw 90 mph, you have to throw with your legs, there's simply not enough muscle in your arm to attain that speed. Arms are not made to throw things at 90+ MPH.