I really wonder how he gonna fit in barca next season.
There is a reason he only broke through very late for a dutch player, for all his qualities he has some obvious weaknesses but ten Hag saw the quality and changed up the Ajax system to fit him.
His biggest weakness is as ten Hag puts it "frenkie likes to go on adventure" leaving the space behind him ripe for counters, ten Hag adressed this by playing with a double DM (to cover for frenkie).
Second biggest weakness is he is always looking for a forward pass and when 1 is not there he takes his time on the ball slowing down play tremendously, ten Hag adressed this by having lots of forward movement and chosing for light weight players with tons of movement (neres, vd beek,tadic) that way frenkie can play forward.
Barca often find themselves against parked busses so double DM is not an option. Plus barca forwards lack 1 quality in general and thats movement (pressing aswell as off the ball offensively) from what ive seen this year, correct me if im wrong. (barca forwards are much better in quality then Ajax though so its not an attack on them). Griezmann helps with that now for sure but 1 guy moving isnt enough.
Koeman was able to copy paste ajax tactics for the netherlands since we find ourselves against opponents that want to play football leaving that space for frenkie and making double dm less redundant. Valverde's tactical acumen will be tested cause he will most likely have to find a new role for frenkie probably as CM.