#1 The Manager
When Arsene Wenger first arrived in England, he took the league by storm and his methods were truly revolutionary. Reams have been written about how he brought about changes by changing the dietary habits of players, used statistics to fine tune performance and provided vitamin supplements in order to ensure that the recovery process was aided.
However, truth be told, other clubs in the league have all caught up with those advancements and Wenger's lack of tactical nous as a manager has proven to be Arsenal's undoing for several years now.
No manager with any aspirations to win the Premier League will ever get trounced 10-2 on aggregate by Bayern Munich and that is only one of the several recent thrashings that Arsenal have suffered under Wenger. He is quite clearly no longer the man to take Arsenal forward and any chance of winning the league under him is nothing more than a pipe dream.
On the other hand, there is no indication that he is going to give up anytime soon and if Kroenke has anything to do with it, then it is perhaps clear that Wenger has a job for life at Arsenal.