Mourinho does some punditry and analysis for a foreign TV station (can't remember which but I've watched videos on YouTube) and he speaks well and makes interesting points. I doubt he's lost any of his tactical "talent" for lack of a better phrase.
I think his problem is that when he's actually in the dugout, he comes across as miserable, and has done for years; I would say around 2014-15, just before things started going badly wrong at Chelsea. At his peak he was never like that - arrogant, yes, sometimes a prick, absolutely, but did have a certain charisma about him and you could see why many of his players absolutely loved him.
When he was at United he came across as totally joyless, always tense and on the edge, and you can only imagine what that's like to work with. It's easy to see why the players were so relieved when OGS took over. Though Mourinho was actually in the right regarding the attitudes of players like Pogba.