He’s been fat since he left houston
Yeah, for the most part. Problem for him is that he is now 32. I am sure all of us have played pick-up with younger dudes who have a little extra weight and they still somehow can jump high and are super-agile. Once you hit your 30s, though, it is important to take your nutrition/training more seriously if you want to maintain that elite level.
I am not saying Harden needs to be Ray Allen, and a lot of his game depends on his craftiness, but this won't go well for the guy if wants to go the marshmallow route.