I've never been convinced by Mascherano, because he always seems to be on the verge of either worldclass or a calamity.
He's a fearless warrior, a real tenacious bastard, and one of the best ball winning midfielders in the world. His decision making though.. sometimes it's just disappointing, against holland several times he made a world class tackle or dispossession, and then promptly gave it away into dangerous areas.
Besides Biglia though, a midfielder who's performances i've really really liked, he's done much better then with gago, as biglia is much better at keeping shape and offering thoughtful energy and cover.