He is good on one v ones on the ground. If people called him a beast based solely on that it could be justified.
But people continue to say he's good in the air despite the fact he hasn't shown any evidence of even being above average. Not only does he not win many, I think he's timid in the air, in that he will not go for headers that Skrtel (and even Agger, despite being derided on here about his ability in the air) would win easily.
I also can't understand how people don't seem to notice this, or choose to ignore it. Even @
dmishra has complemented his heading ability already in this thread (and he's normally a fairly good judge of a player).