He is just one piece of the sucess. He have chosen well the players (as usual).
Just look at Porto last year, and this year. Last year won everything. This year, spent even more money on players, and lost everything (or almost, as the portuguese league only ends next Saturday).
Players like Derlei, Maniche, Costinha, Nuno Valente, just become ordinary players withou Mourinho. How do you explain that?