I don't see whats so bad about his transfer, former la masia player who got minutes at ManCity and plays for Spain. Most clubs would at least think about a former academy player like him on a free transfer, not much to lose there. If he fails he fails, who cares just sell him after a season or two.
The real problem is that Umtiti is fucked, yet still here earning a fortune even 3 years after the world cup that basically ended his career and 36M transfer Lenglet somehow being so bad that he fell behind the youngsters in the packing order. So that leaves us with 34 year old washed up Pique and the kids.
If Umtiti still had kness or we actually managed to buy a good CB in the meantime then Garcia as #4 or something wouldn't matter that much. We also meme about Braithwaite and Luuk de Jong and yeah they are shit as well, but also just tiny pieces compared to the colossal fuck ups Dembele, Coutinho and Griezmann that costed the club 400M.
Some players will fail, but what brought us in this situation is that pretty much no bigger transfer in recent years lead to a long-term starter. It's honestly incredible to fail that hard, almost impossible but they somehow pulled it off.