My theory is that Rojo would be absolutely shat on if not for a couple of reasons; (a) he's a new signing, so avoids the grievance that others have towards Evans/Jones/Smalling where the fact that they haven't progressed from being very highly rated youngsters is held against them, (b) he's got a Latin name and is covered in tattoos so people think he's some sort of ball-playing, composed defender that is in vogue.
He gets a lot of praise from some elements, but I don't think he's very good at all.
My main gripe is that he's not imposing enough at all. He's 6 feet nothing, average build and doesn't attack the ball in the air. Smalling and Evans are taller, whilst Jones is built like a tank and is more aggressive in the tackle. Kevin Davies constantly kept manipulating him and kept the ball well away from him, and he couldn't handle him (see build up to their first goal). When the ball is dropped on top of him from deep he very rarely gets a big header away. Then there's the positional mistakes, silly tackles and suicidal passes out of defence. He's also rash too, I'm thinking of how he managed to dislocate his shoulder in a slide tackle.
He's not crap, but I'd honestly rather Smalling/Jones at the back. Rojo should be CB/LB cover at most for us. He reminds me of Silvestre, but two inches shorter, with less pace, and without the crossfield passing.