Regardless of how good anyone is at their own job, if your boss gets you to work with people who are not specialists in their field then the team is going to struggle isn't it? If he picks a taxi driver to be your accountant and a chef to be your crane operator you are in trouble. If he hires 15 truck drivers but only one digger driver you are going to have difficulty shifting what needs to be shifted.
The manager of a football team picks the side and decides how its going to play and he selects the personel he wants to fulfil each role. If he gets it wrong, inappropriate formation or players not in positions they excel at, then its turns into a car crash unless the opposition is considerably weaker all round and the shortcomings of your managers choices are outweighed by the skill of the players.
See what you,re saying but it wasn't like he was playing Rooney in goal and Terry on the wing. There were several unusual decisions like why the hell Crouch can't get a game under him, and why Joe Cole is constantly overlooked. But the rest play for top club sides in this country.