How good a fighter could David Haye have become if he didn't have a rubbish coach?

Haye acheived WBA, WBO, WBC, Ring Magazine undipsuted Cruiserweight champion status with Booth. And as a natural Cruiserweight, went up to heavyweight and gained a WBA heavyweight title belt. So it's not like he achieved nothing.

Hayes main problem is getting more fights. He hardly ever faught in his career.