I think Arsenal fans should be upset that they didn't sign some quality in depth. You cannot expect Fabregas to play every game of the season - not even Steven Gerrard (who would play through the pain barrier for Liverpool) could.
And last season, Arsenal fell out of the title race because of a lack of depth. And then experienced players are sold, with youthful replacements signed.
I would be seriously upset with the Arsenal board if I was an Arsenal fan.