You don't know what he's up to behind the scenes, what his issues are and how his body is reacting to them? Has he got a lagging injury he's trying to shake off? The groin is well known to be a real hassle to clear yourself of.
It was only a month or so ago people were saying we wouldn't keep hold of Lo Celso. All of a sudden he clicks and many see him as an important player now. Let's give Tanguy a little time as a young man findinging his feet in a new plane and a new style of football. We don't know the situation so to judge it wouldn't be fair.
Everyone who observes Kane's condition when he comes back from a prolonged absence due to injury can see he put in the time and effort to remain fit and well conditioned to do a 90 minute game when called upon. It's an obligation to his club, supporters and himself. On the contrary, Ndombele does not look fit and as evidenced from his huffing and puffing after being on the pitch for over 15 minutes, it is not because his "body just looks that way". that is a pretty big problem for a guy who also participated in a full pre season with the team and raking in 175k a week.