With a patch of fur missing, I wonder if he was in a fight, and if so, does he have injuries? He may be lying low and staying quiet because he is literally licking his wounds.
The fact that he came home at all is amazing.
The bare patch is just missing fur - the skin isn’t broken - and he didn’t object to being picked up, which he would have if something hurt. I think he’s just tired and stressed out. If he’s not acting like himself after the weekend, I’ll take him to the vet to be looked over, but it’s not an emergency.
We see “Lost Cat” signs sometimes, and I often observe that cats really don’t get lost, they just decide to move out. However, cars, dogs, coyotes, and other hazards are always out there.