Of course. But you could see his presence improve or dictate a game. The bloke is a bulb, but his impression on the most successful PL club in history is as much as a measure as someones obvious talent.
Viera was the same at Arsenal, Adams as well, but Keane did it for longer.
Oh yeh no doubt they're all great players; Vieira is my all time fave, just not sure they fit the category of 'winning a game by themselve'.