It depends on what systems you play. In systems where you park the bus often and your CBs spend most of their time inside and around their own penalty box, you don’t need a lot of pace and instead positioning and awareness are much more important. Also in compact systems where midfielders and the defenders are not too far away from one another and they cover each other well pace is also not that important. In a system like ours where we play a pretty highline and our defenders and midfielders often push out even to the other half supporting the attacking game pace would be important, as we have often found out in the past that our opponents often hit us in the back via a long pass behind our defenders or they quickly cut through our often non-existent midfield, which resulted in our defenders, especially our CBs chasing the ball a lot. So we would value a pacey CB. Not saying it is more important than everything else but it is important.
Ajax and Barca play the same way. So De Ligt would be a perfect fit. Barca would feel like home to him.
Him and Frenkie could have been a great duo.
But i don't think Juve is a bad choice either. He's outside his comfort zone now. Playing in a different system.
Now he has to pass the ball to Matuidi and Emre Can (both can't do shit with the ball on the feet).... or long balls to CR7 if he's desperate. It will take some time to get used
But in the end, playing a different system will only make him a more complete defender.
Playing for Barca would have been much easier for him. But he chose the harder path. Props to him.