Got to agree.
Utilising players to their strengths rather than forcing a style of play gets the best out of a player. Also motvation of players is another area where a manager has a big influence.
Just look at Smith with Le Guen. Made a couple of key signings (Webster, Weir, Ehiogu) to plug any obvious weaknesses (ok so we spent £2m on Thomson in that window as well).
We'll most likely never find out unless Warburton walks (doubt that will happen) or he gets poached by another club down south as the board won't spend any money sacking him.