No-one’s really debated this properly, but this is what you get when you fiddle with the meaning of the offside rule.
In the olden days, Tevez would have been flagged off probably before Messi even hit the ball forward. Linesmen would have been conditioned to it, seeing one guy so far ahead of the defenders, and there would have been no debate. Now, in a high pressure situation, linesman possibly sees Tevez in such a position, but he supposedly isn’t interfering with play. The linesman wants the game to continue, as he reckons Messi is bypassing Tev and shooting anyway, so it isn’t really an issue. Yet. As soon as Tev touches the ball he becomes 'active’, and in the confusion, the linesman really can’t be sure exactly where Tevez was a few seconds ago when Messi kicked the ball. So he takes a guess, giving the benefit of the doubt to the attacker, as the rule encourages. The rule was changed to encourage more goals, but it’s a wonder it hasn’t created even more illegal goals like this.
Wasn’t there a goal in the Merseyside cup final where Tony Cottee actually ran back into Liverpool’s goal to avoid being offside, whether Stuart McCall’s shot hit him or not? Those were the good old days, you knew where you were. As Bill Shankly said, 'if you’re not interfering with play, what are you doing on the bloomin’ pitch?’ Nowadays, free kick routines with one attacker virtually standing on the keeper’s toes confuse the hell out of me.