Why does time matter? Messi has surpassed many footballers in the past 15 years already, we're not debating longevity are we? I've not seen many people better than him in general, much less at his age, this fast, with this much potential to grow. If it was Pato, fair enough, he still has a bit to go to prove he can keep it up. Messi's hype period has passed and he's still living up to it, surpassing it even, in a team of floundering greatness.
As for Toure, like you said, defensive effectiveness. He came from playing for NO club, essentially, to being one of the world's best defenders. How you don't rate him is ridiculous. I could say the same for you, though. You support Spurs, I find it ridiculous to deny Fabregas. Van Persie I'll give you.
-AC