First off Sofyan Amrabat is no longer Manchester United player because they didn’t activate the buy option, Casemiro is there but just as you Said the Brazilian actually did suffer with fitness problems last season and his inconsistency did cost Manchester United a lot, i was part of those who even thought he should have been sold this summer to the Saudi league to help Forster funds for new signings but he wasn’t and with his performance in the community shield and the first league game against Fulham I think he should have this year. Manuel Urgatte is a potential and with proper management could develop into a good defensive midfielder, I got a good look at him at the Copa America with Uruguayan national team and the deal seems ok to me most especially since it is even a loan option first.
Sofyan Amrabat did not play as expected by Man United, either because he did not fit into the English football culture or he could not adapt quickly, that is why Man United was reluctant to sign him permanently. While Casemiro was actually an option when Man United failed to sign De Jong at that time, although in his first season Casemiro played quite well but he could not be consistent in his second season, so I think Man United is hesitant to entrust the midfield to him, and that is why Man United is very insistent on bringing in Ugarte.