The whole we could've signed them earlier argument is bullshit. Not every Ajax youth player is willing to leave, Ajax is an excellent club to be at for their development, most of them get offers but many stay. And look at what's happening with Fosu-Mensah, he was just as talented as De Ligt and there's no doubt in my mind he'd be further in his development had he stayed at Ajax. How many 19 year old central defenders are starters at top clubs in the Premier League? De Ligt most likely wouldn't be the player he is right now had he joined Manchester United, he probably wouldn't have got much playing time let alone be a Dutch international starter.