At 20 he already broke the record for most assists from a PL defender. He was gonna break that record once again before the season ended. He has more assists in one season than an elite playmaker in David Silva had in any PL season. Outside of Hazard's last season with Chelsea, he has also produced more assists than him in any single season.
TAA is only 2 years older than Dest, who he is being compared to in this thread.
And Barca, if they want a player who can turn it up defensively are probably better off getting back Emerson from Betis, who has produced more in a stronger league than Dest so far in their careers AND called up for the Brazilian NT.