As I've said before, getting recurring muscular injuries after a long time out is a real risk, because they end up overcompensating for weakness, or simply recurring in the same area(s). It's what I was most worried about with this guy, I was actually surprised he played so long and at that tempo against Inter, I suppose it was too good to be true.
It's a bit of a two sided coin, but getting a full summer of training should get his core fitness back up before we go into competitive games.