We all have the benefit of the TV cameras to show replay after replay, but the ref had to go on his angle, and the fact that it looked like Arteta had elbowed him in the face. Add to that Fabregas rolling around like he had just had a leg blown off by a land-mine (now compare that to Arteta's reaction when he actually got elbowed in the face playing Bolton, with a mouth full of blood. No rolling around, just touching the lip as if to say 'Bloody hell, he busted my lip open')