It's literally the opposite.
I've seen quite a few posters on here trying to convince themselves and others that this is actually great business to pay 51m for a player who's limited on the ball, not a high volume passer, not a progressive passer, arguably his in-possession actions consist mostly of passing to his nearest teammate, he's not a great ball carrier, he's not elite at ball retention, he's not gonna be much help neither for our own transitions (because of his deficiencies I've just mentioned) or against the opposition's transitions, because he's not a player who can cover big spaces quickly, and that's one of the biggest things our squad has lacked for a while, but we'll see how the new signings help us in this regard, especially Yoro. He's a good ball winner, he has a lot of energy and stamina, and he seems to be a tenacious character on the pitch.
However, he was never worth 51 million in the first place. That's probably around his peak value if he develops his game and becomes a better player than he currently is within the next few years. However, not did only PSG already overpay for him 12 months ago, we are seemingly willing to do the same 12 months later when he wasn't anything special for them, and their manager doesn't rate him because of his limitations on the ball and in possession, so he's not gonna play much if he stays and he's absolutely not in their long-term plans.
It's the opposite of great business, in all likelihood. I'd call it decent business if it was a loan without obligation, or a ~30m transfer fee. For 51m, though, he needs to be a huge success and show more than he has for PSG, which would grant him a long-term key role in the squad, which isn't there for him IMO currently.
Also, him in a double pivot with Mainoo or anyone else in the current squad could lead to build-up problems. Mainoo is good at progressive carries, but he's not a great progressive passer IMO. Neither is Ugarte. And since we've just extended with Bruno for 4 years and put him onto 300k per week wages, it's not likely we want to move towards a 3-man midfield with a progressive + high volume passer next to Ugarte and Mainoo anytime soon. If we had someone for that role, like a Cole Palmer, and/or someone to play #6 behind Ugarte and Mainoo, this would be a different scenario, because then Ugarte would be adding good tactical flexibility to the squad IMO, although I'd still not believe it's great business for 51m. Right now, it seems like he's coming to play a very important position for us for big money, whilst being a limited player we might well be looking to upgrade on 12 months from now.