Ibrahimovic has 6 yellows and a red (which wasn't a red), Eto'o had 9 yellows last season. Did anyone ever complain about Eto'o's cards? No, but they weren't so obvious as Zlatan his cards. Perception. Just as you say that Mascherano collects them as a hobby, while he has a quite moderate record of cards in the EPL. But he looks like a nutcase, so you will pick on him.
Not to mention the reason why you pick on him. Cause of those cards? Of course not. But because he might replace your beloved Yaya, so everything negative has to be brought up about those players. This has been going on for quite some time now, Busquets, Mascherano, ... whoever comes to replace Yaya will always be the subject of some crap in here for that reason only. It happened with Zlatan this season, cause he replaced Eto'o and because the club broke the bank for him. That was enough reason for some to TORCH THE MOTHERFUCKER! I WANT MY FAVOURITE BACK!
And then finally the logic:
Is Mascherano more aggresive than Yaya? Definitely. That's the bitching reason Pep wants someone like him at Barcelona. So we actually have a player at that position that goes for it every game, like Busquets does. So we have a player that injects energy and adrenaline into the squad (same role for Alves, he pumps up everyone just by his energy and nutcaseness) ... Pep would welcome those yellow cards. And so would I. I rather have someone picking up some cards than costing us three goals on a season.
Yaya is a favourite of mine but I can't be bothered to see him in Blaugrana next season. 09/10 was very disappointing for me, on as well off the pitch, and it doesn't seem to get better. Nor will his agent leave the team alone. And I choose the team over my favourites. So Yaya can leave and Mascherano can come for me.