you don't draft a guy who looks like a whale when he's 17 years old and hope that he suddenly drops 50 lbs. most players get thicker, not thinner, as they get older. by most accounts, he's actually in better shape than he was during high school. he's always going to be fat or at least chubby, so you can pretty much assume that he's going to be a minus baserunner and first baseman. the hope is that he turns into a 30+ hr, high OBP guy and that overcomes his deficiencies in the field and on the basepaths. I've seen plenty of instances where fatty 17/18/19 year olds get into much better shape in their 20's. It's not that hard to do. As for their leverage, they decide if/when he gets a promotion and if/when he gets called up to the majors. They have plenty of leverage to try and force him into better shape.