For the first part... Are we really criticising him for not flourishing in a front line which contains a career defensive midfielder, a career left wing back and an 18 year old kid? His performances when part of an attack containing 2/3 of Neto/Cunha/Hwang/Bellegarde have been more than good enough, in fact he's created chances at a higher rate than most forwards outside the top 6, but it's only natural for his performances to slide when he's playing alongside weaker players.
As for him not doing a lot elsewhere... He was excellent for Getafe (as a kid), Sevilla and through the Spanish youth systems so I'm not sure what you're getting at.
I'm not sure what else he can do really. He's part of the 'leadership team' but he's never been one to carry a whole team on his back. All this criticism of him lately has been massively unfair IMO.