I found the recent Nasri quotes quite telling - that Pep will not pick you if you are more than 2kg away from your expected weight. It shows that Pep has very stringent views on everything particularly sports science, which drives players to be the best version of themselves. If they don't agree they are gone, not a bad thing in my opinion. Add the emphasis on being a good team mate even when not in the side - see how Cancelo was bombed out - I think it's all up to Kalvin if he wants to be a success with us or not.
I would advise him to take note of how Jack for instance has conducted himself - yes he has fun on his days off but you would be hard pressed to find a player who works harder at fitness and being in his best shape every game. I also think that those who moan because he is seemingly happy just don't get the mood that Pep demands of all his squad. He has talent but if he comes back in pre-season slightly overweight or not in the best condition he will be gone. I for one hope he takes heed of what has happened this season and comes back to show his true potential.