Arsenal's tactical development over the course of 2015 has been bookended by the sudden rise, and the recent demise, of the Francis Coquelin-Santi Cazorla midfield combination. If their initial improvement was a complete surprise, the recent loss of both through injury feels entirely predictable. Fitness problems have dogged Arsenal for far too long and with Alexis Sanchez also ruled out, Arsene Wenger will be forced to rethink his team selection entirely at the start of an extremely busy month.
A year ago, the idea that Wenger's favoured deep-lying midfield duo would be dependent upon Coquelin and Cazorla would have been ludicrous.