This is a bit unfair I think. First, why can't early playing time be the answer to how they will develop him? Summers can point to DJ Humphries as a recent 1st round draft pick at tackle that he was responsible for developing (but was underwhelming while here), and no doubt a ton of other NFL Olineman that he coached up while at USC and elsewhere during his long career. Let's not pretend these guys don't come in with a wealth of knowledge on technique, concepts, off-field stuff, history of success in putting lineman into the league, etc. etc.
When Leatherwood says "develop", I believe he means "get me drafted in the first round." Guess what? No matter what the coaches said, they weren't convincing this kid that they could "develop" him better than Bammer, who year in and year out gets the best offensive lineman in the country to commit and year in and year out gets its lineman drafted in the first or high rounds.