He takes shots from his chest or shoulder. Ball is too low and opponents know they can either block it or foul him with little consequence at the line. And, when he does take the ball to the rim, he's not exploding vertically. Seems like, unless he's completely wide open, his objective is a lay-up. So, ball held low, and no lift = blocked shots.
His other issue is that he's frequently shooting while in a twisting/contorting his body position. His form is whack, and he's just 'putting it up,' hoping the touch keeps it close to the rim. He's rushing those shots because he's so used to getting the others put back at him.
Here's a cheap pop-psych analysis... I'm thinking he's a gentle giant, and too used to Trying Not To Hurt the Smaller Kids. Put those elbows out, DC. Protect and go up with conviction. Forget about making those calculated moves each time. Play it like Keita - he doesn't mess around with the ball. If you're in the the paint, that's close enough - forget the dribble and drop steps. Just square up. And anything at the rim: dunks only. No pitty-pat stuff.