Football fans in general have a tendency to be capricious, some switching their opinion on a team's manager on a weekly basis.
Social media marketing company Gravity Thinking created this graphic illustrating which was tweeted more over the last year, #WengerOut or #MoyesOut. A simple but interesting metric to see the up and down nature of some football fans' moods.
The major spike on the graph is for #Wengerout, probably around the opening day of the season when Arsenal lost to Aston Villa at home and Arsene Wenger had only brought in Yaya Sanogo. The #WengerOut brigade quieten down after that though, as Arsenal went on a nine game unbeaten run and signed Mathieu Flamini and Mesut Ozil. There's still a small minority of #WengerOut tweets but that was probably just Piers Morgan.
The spikes for #MoyesOut are numerous, though there is a lull around October and November where Utd went on a three game winning streak in the league, including a win over Arsenal.