Whats not to love about such "exclusive" opinions. Mate, each to their own of course but I am sure, you'll have serious difficulties finding a football fan away from United who wouldn't say that this is bonkers. Rice and Caicedo went for crazy money, granted but both are superior players to McTominay. Especially Rice.
Just look at McToms fbref... It is carried right now from his goal contributions that are very high.
His ball progression isn't even mediocre - he is 8th(!!!!!!) percentile for passes attempted, 7th (!!!!) percentile for progressive passes. Pass completion 50th, Carries 67th, takeons 56th. Touches in penalty box is 83th.
Defensively he is very much below average, 58th for tackles, 29th for interceptions. Blocks and Aerials are 82th and 84th. Clearances is 98th, probably connected with his heading.
All I am seeing is a below average CB, that is trying to act as a midfielder but is best being used as some sort of battle ram 2nd striker. But I wouldn't consider myself a fan like you. A player like him has use but certainly not for a club like United that is trying to get back on the horse. Do yourself a favor, look at his fbref profile. And compare it with Caicedo (also a bit unimpressive but clearly above average where it matters) and Rice (who is pretty well suited for his role).
McTominay Fbref
Caicedo fbref
Rice fbref
McTominay loses out everywhere, eyetest or stats.