I wrote this in the match thread
But James has picked up a lot of minor injuries in the past. I want to believe that maybe it was due to the style of play that was required of him at those clubs since he had to adapt his game and play as a CM and press and run a lot. He grew up as a 10 in Colombia and I don't think his body really ever got used to that.
Carletto seems to have freed him of that duty by playing him as a true attacking midfielder. Maybe and hopefully that leads to less physical stress and less injuries.
Ancelotti also, from memory, has quite low intensity training sessions which might help him.