I think our friends from Cardiff might have something to say about that. If he was THAT good, why aren't you top of the league?
"Thus we may know that there are five essentials for victory: 1 He will win who knows when to fight and when not to fight. 2 He will win who knows how to handle both superior and inferior forces. 3 He will win whose army is animated by the same spirit throughout all its ranks. 4 He will win who, prepared himself, waits to take the enemy unprepared. 5 He will win who has military capacity and is not interfered with by the sovereign.” ― Sun Tzu, The Art of War "Thus we may know that there are five essentials for footballing victory: 1 He will win who knows when to play 4-4-2 2 He will win who knows how to handle both superior (Leicester City) and inferior (Nottingham Forest) forces. 3 He will win whose team is animated by pre-match Haribo consumption. 4 He will win who, prepared himself, then walks like an Egyptian. 5 He will win who has nepotistic capacity and is not interfered with by owners trying to stop him playing his own son in midfield.” ― Char Li, The Art of Farce
Because he can't help silly mistakes made by the players. He also doesn't play every week. Mind you, he isn't in a fit, physical condition to anyway!