Same thing was said about Son in 2015 for 22m. Give him some time, he will develop.Admittedly this is a stupid point, but if we had bought him for 25m then I'd be fine. It's just 40m seems quite expensive right now.
I also think him and Son are too similar and having both in the team is asking the rest of our already knackered and depleted players to work harder. Of course, we have no choice right now but to have both I feel we need a fully firing midfield.