Even if it was his fault, I don't see what's your point.
He's an AMC, he's not expected to know how to mark players anyway.
If it was Giovinco playing as a right-midfielder (another AM, just like Candreva) and failed to mark Riise, would the reactions here be the same?
We have three of our defenders going at the single attacker in our box. I blame the defense here and the coach who knows shit about setting the defense, even though he himself was a great defender.