If you were an coach, and you knew you had it 'all over' a bloke from another team, and, - knowing that fact - meant you got a win every time you played them , would you sit there recommending that your opposition replace the other bloke as coach.??
Or would you 'blow wind up his a..e" in order that your dopey opposition keep hold of him??
Its a bit like trying to get rid of an assistant coach that's useless by telling everyone else he's great. (....I am looking at you Sydney circa 1998...)