A health warning: Arsene Wenger is a great manager. His record will be lauded when he retires. And, as will argued later, he stands alongside the likes of Bill Shankly as a club builder.
However, he is human. The cult of the personality of the manager, which possibly started with Shankly, has grown to such an extent that there is little room for nuance. They are either gods or devils. Twitter doesn't really do shades of grey.
All managers have flaws. And as Arsenal prepare to take on Bayern Munich in the Champions League, it is in Europe which Wenger's are most painfully exposed.