I don't think it's a question of Messi winning a World Cup, because individuals don't do that, but only as part of a team. Pele played in a magnificent team, Maradona in a more ordinary one. Johan Cruyff never won a WC winners medal, but everybody accepts that he's as great a player as you'd ever see. Puskas, di Stefano, Zico.
But Messi didn't play great football at this World Cup. This is the measure. Same for the Portuguese Ronaldo. Now, he can say he was injured but even still, he's never played a great WC and this was his third. Messi was fine in spurts and against Iran and some other heavyweight team he scored great goals, but when it came to shaking down the medals, he didn't make any difference at all. He was marked out of it against Holland and though he had more room against the Germans, he wasn't able to make an impact.
So I don't know, Maradona and Zidane and Pele and Cruyff all raised their games in the WC, and Messi didn't. I don't even think he was Argentina's best player. And before anyone says, oh, the marking and fouls, please look at the treatment Maradona use to get.
But to me, it's not about goats, which are always based upon bias. It's about this: did the guy perform great at the very highest levels of the game?
Yes, with Barcelona, but not with Argentina. And we can say that with Argentina he didn't have Xavi and Iniesta and all the rest of them, but even still, he had a fine side. So, he's definitely a great footballer, that much is evident, and he's one of the best we've seen, and I'd say he's most likely the best of this era, but it would be silly for anyone to say he's the greatest footballer who ever played the game...