ESR is a superb footballer, but it's not enough these days. Athleticism is too important and he didn't quite cut it. I imagine that's why the friction with Arteta during his long relative exile at Arsenal.
Emile would've felt like he was doing all he could. Meanwhile Arteta would've been confronting the grim private insight he wouldn't be able to make room for a player that gifted if Emile was going to have trouble staying adequately fit, fast and injury-free to compete for selection at the best football club in Europe.
The levels index the ambitions we now hold as a club. The next preternatural talent to fall foul of these sorts of obstacles to greatness could be Nwaneri for example.