No just No, I wouldn't even class him as average. He wouldn't start for the top 15 teams in the league so why would you keep him.
I don't mean to attack you personally but I'll say in general, you fit the hyperbolic nature of a decent percentage of our fanbase who want to throw the baby out with the bathwater everytime we go through a bad spell.
Of course McTominay would get a game in other top 10 clubs. Sure, he's not world class but just because we're a dysfunctional side, doesn't mean some of our players can't perform well in a functional one.
McTominay is strong, athletic, decent in the air, strikes a ball well and can actually ping a pass. What he lacks, for a top CM, is the ability to play on the half-turn, so only really tends to be effective in straight-lines.
The players we need to get rid of are the players who can't compete physically. For me right now, that's Pogba, Ronaldo, Mata, Matic, Rashford, Martial, van de Beek and most likely fringe players like Amad and Pellistri. Fred would also be on my list, but not a priority right now.
Note when I say "physically", sometimes it's not the same trait they lack. Pogba, for example, is strong but lacks intensity/aggression. Rashford is quick but lacks intensity/aggresion. Fred has intensity and some aggression but is physically small and weak.
Then what we need to figure out is how we bring in players who are both athletic AND very good footballers. Then we'll have a monster of a side. However, to get back to the point, "athletic but only slightly above average" will go further in the PL than "talented but not athletic"....hence I'd keep McTominay just for now at least.