Just to put this out there, there is probably a case for why Pre Resets Sensei appeared to be more "put-together" than he was in the Resets. It was likely due to the one thing that Sensei lacked in the Resets:
His relationship with Maya.
Ami kept Sensei alive by basically doing everything around the house, making sure he was fed, waking him up, etc, but Maya was his stress relief and more or less therapist:
Maya also seemed to control him in a way that lead to him staying away from other girls (Noriko, in particular), and ignoring those voices in his head. Black-outs and Hallucinations aren't anything new as Maya Prime pointed out in Chapter 3's 'I Won't Say I'm In Love' Main Event.
Sensei, in the Resets, lacked part of this system that had kept him functioning for years, along with his memories of those years, and had nothing keeping his worst impulses in check.
This would probably be a reason that Sensei seemed more "put-together" Pre Resets. He had a system in place, that required Maya, and it kept him stable.
In the Resets, this System was neutered and Maya couldn't even tell him she loved him without breaking him. Current Sensei started out basically trying to fill the void left by her, with whoever or whatever he could.