What you just described isn’t what you call a kick up the backside, is it? If he meant what you said, I would imagine him describing that more as furthering his development as a footballer/ making him a more complete player etc. A kick up the backside implies he didn’t feel he had enough pressure to perform at Arsenal or that the manager did not demand enough from him. My criticism was towards that. If he felt that way, then he didn’t need the manager or anyone else to tell him to do more. If he didn’t know what more to do, or how to do it, then fair enough, but like I said, I wouldn’t describe that as a kick up the backside, more along the lines of improving as a player, becoming more well rounded.