I think a lot of people don't realize how good he really is. And you obviously never know how a transfer is going to turn out, but he's about as close as possible to a "sure thing". Unlike the vast majority of our supposed targets / signings as of late, this one would actually make sense.
That being said, the numbers being mentioned are pretty steep. Coupled with the fact that money is tight, I understand why people are hesitant.
If we put this as 55m deal, with 5 years installment it means 11m per year, almost the same with Morata's loan + option(20m loan +35m option) , but we ended up not take the option
If in 2 years we sell him for around 35m basically we done the same deal on him.With installment this can be categorically cheap transfer for someone who command 20 goals contribution per season, mostly fit with 50 matches. If he actually keep his form with us, we can sell him for 50-60m later and recoup all investment on him.
With Koop arrival, we actually have a quite formidable midfield with Douglas Luiz and Kephren Thuram, the only doubt left is how fast they can absorb what Motta want from them. For the first time in year we actually address our midfielders situation
If we really want to pennypinching more, we can do 5m loan + 50m obligation paid in 5 years installment, but doubt Atalanta will entertain this structure. Next year or this year, one way or another, most of our leeches already gone, so we should be in a better position financially, especially if we can qualify from UCL group stage and get a fairly lucky easy draw and go far in UCL like Dortmund last year (more money income)