He hasnt become irrelevant, he is still a big star, but he is not living up to the potential of becoming a super star tho. He is not willing to put in the work, and with low iq play style like his, it shows clearly what a massively well prepared and organised world class team you need to get the best out of supreme talent like him. Because thats what he remains, a talent, huge one, that thinks he can only coast by his skills if you dont have a guiding hand that limits his flaws/puts in a position to only excell at what he does best. Mourinho is NOT that guy, neither is is the quickly put together squad Man U has. So yes, he is getting paid well, and no he isnt lost his name, but its defenitely taking a hit on a footballing level. Because we saw this awful type of Pogba with us 2-3 months or so, until he simply took over games because he was given the support and freedom to be a HIGH impact luxury type of highlight reel player that gave us tons of wins, and insured he became most expensive ever. I dont think he is the type of personality who will ever mature more as a player despite the insane skillset he has (there is nothing he cant do in both directions), so he essentially he needs a set up like ours again.
And again, no alibis, but MOURINHO IS NOT THE COACH for player like him. He wasnt the coach for De Bruyne either, and so many others before him.
I can easily see Pogba going to Real or PSG and just taking over games in finald third like he did with us. Because something as simple as playing him in 3 man midfield and telling go roam, these guys will clean up after you lol. Deschamps didnt realize this either and used him in 2 man rigid CM duo, they are either blind to his tactical and football IQ type of flaw, or they dont think he is worth adjusting to. Either way, its silly. I think it took Conte like 2 games TOPS til he realized it was absolutely retarded to play Pogba in a static role, think he filled in for Pirlo as regista/DM couple times and looked completely clueless in that role. While with Allegri, one of the most devastating Pogba performances I seen is games he played AM infront of 2-3 CMs where allegri simply instructed him transport the ball forward, and he was a scary Yaya Toure esque freight train (think of those games were vs Torino).