Wilder

I'm not sure it would have made a difference if the rumours about Wilder's ego are true. I've heard a few people from various camps comment that Wilder often refused to listen to trainers and take on advice.

You can't improve someone if they won't listen. Wilder seems to have suffered from the age old problem many big hitters suffer from: they think their power alone can win them fights and get them out of any tight spots so they don't spend enough time working on the rest of their game.