I kind of agree with you, but how do you think we would do with Guardiola in charge if the forwards he had to work with were HRK, Montero and Anichebe?
I did say “the right Manager / Head Coach†clearly the likes of Guardiola would, initially, find difficulty coaching the quality of players we have and the type of football played at our level. No doubt he would learn and adjust accordingly, because he is a world class Coach.
Regarding the players you specifically mentioned, it is unlikely any Manager / Head Coach would be able to improve their footballing skills and, particularly, their techniques at this stage of their careers as they are all ready ingrained in the player, bad habits and all. The only thing he might be able to tweak is tactical aspects of their game.
And if is was between keeping those players and a good fit Head Coach for us, it would have to be, in my view, bye, bye players, welcome new Head Coach