You should watch it again, it's actually farcical how Arsenal throw every man forward, you lost that game same manner as you lose every big game, the fact that Rooney can play Di Maria onside by passing in his own half is just laughable.
The finishing from Arsenal was woeful until Giroud came on, Wellbeck his usual wasteful self and Wilshire couldn't finish his breakfast.
It will always be one of those days if your just going to set up exactly the same every time you play a big rival, Wenger was found out about a decade ago but has still failed to adjust, it's painful to watch at times as he's clearly a talented manager but it looks like change is beyond him.