my boy dali says some crazy things, but he has a very good point about managers. with a (more or less) level field of players, they aren't more important than players.
obviously when you have some part-timers playing world cup winners (or other mismatches), the coach will have to help compensate that difference in quality with tactics. but in, say, barca vs. inter... yes the managers are important, yes their contributions are crucial, but it's the players who win and lose the game. all a manager has to do is not be a complete idiot and trust his players to get it done.
the greatest sides in history are full of players who were given the freedom to lead on the pitch and are remembered for their players, not their managers. they were sides that had freedom of expression.
managers perhaps affect 90% of their team's performance, but it's the shallow end. that final 10%, the deep end, is the players. and while they affect less than their managers, they affect the most important part - the actual playing of the match. mourinho, for all his brilliance, came within a diego milito injury of being the new bayern leverkusen. for all his genius and posturing it was four moments of brilliance from milito that won the treble. for all pep's genius we only won the treble thanks to that little pale guy from la mancha and that one kick he took at stamford bridge.
players decide games, and the best managers will tell you that. pep's constantly deflecting praise from him to the players.
