I don't think there's any manager out there who wouldn't take Casemiro in a heartbeat. Even Pep wouldn't say no to the idea and he's got plenty of options in the midfield. Of course, managers have priorities. ETH was not wrong in his assessment of our midfield. Even with the signing of Eriksen, this team is crying out for a CM who can operate adequately between the lines on both ends of the pitch. His initial "mistake", as he was saying in the pre-season interviews, was that he thought of Fred as the "connector" between the defence and the midfield. The player who would provide the first pass out from the back to either beat the press or progress play. Something that, IMHO, added a flavour of "panic-buying" to Casemiro's transfer. But we did act. We took a suitcase full of money and we started knocking on every door for a solution to our problem. Solskjaer had both the time and the money to address the same issue: The difference is, he didn't.
I will agree that Solskajer wasn't overly happy with McFred. On the other hand, i also believe that he used to perceive the midfield less as a riddle to be solved and more as a nuisance that had to be dealt with. That's probably one of the reasons why he never truly invested in it for almost 3 years. He wasn't dogmatic as many believe, he was more than willing to go back to the drawing board when things weren't going well for him. In this sense, Matic proved quite useful in our build-up after project restart with his ability to drop between the centre-halves and pick out passes. That wasn't the product of tactical acumen, though, but an attempt to patch up the issues Maguire's (and Lindelof/AWB) dithering on the ball were creating. And he also wanted Pogba's vision and his exquisite long-passing range to create chances for a forward line which consisted of players (Martial, Rashford, Greenwood, Cavani) who are all at their best when they can be direct and exploit open spaces. Solskjaer could see all of that. But between a defensive line that feels safe when defending deep and a frontline for which work rate seemed to be an alien concept, the spaces in the midfield became huge. Thus, McTominay and Fred came into the picture. There's a reason why these two are associated with Solskjaer's time at the club, just as Fellaini is associated with Mourinho's tactics despite him being a Moyes signing. They ended up being a necessity for us because the overall plan was deeply flawed.
In the end, Casemiro is an integral player for us, not only because he is a world-class footballer, but because we're maximizing what we can take from a player with his attributes. Notice that ETH rarely mentions how much space Casemiro covers on the pitch. He prefers to talk about his passing abilities, which allow our #8 to position himself closer to the attackers and between the oppositions lines. He also describes him as a "possession-safe" midfielder, one who can be an outlet and provide a numerical advantage in the attacking half. ETH shouldn't be rendered some kind of genius for mentioning these things. Casemiro had the very same qualities in Madrid. But the difference between great and good/average managers isn't in who they buy, but in what they buy. You can spend a fortune on Casemiro to create a midfield like the one ETH is trying to build. Or you can spend it to buy the luxury upgrade of McTominay on the pitch. Both things are possible. And that's why a lot of people on here were screaming that, despite the consecutive top-4 finishes, we were going absolutely nowhere with Solskjaer.