I've heard that as well, when they asked Cotto if this was true, he didn't comfirm nor deny it, he said he was open to add and improve his team. I don't think Steward would be a bad choice.
I think Cotto would be very receptive to stylisitic changes. He is a very good athlete and does a lot of things well, it isnt as if he has "fixed" style of fighting with bad habits or fundamental flaws. He needs to shore up his defense as has been pointed out, I believe brother Nazim could really do some great work with him.
I think Roach would be great but with the Pacquiao fight coming up you can scratch that. Nacho would be good also but i doubt that would happen. Cotto doenst need "MAJOR" changes. Just to touch up on his defense cus he is way too open for the uppercuts. There are rumors that Emmanuel Steward is going to be his trainer but i dont know how that will work. Maybe it can be a good change.