Missing height and heading ability to compliment to lets say Lindelof.He could be Lindelof replacement..Koulibaly is 1.85,no more,never was great in heading the ball which would be seriously exposed in Premier league with him partnering Lindelof if Lindelof is the one we aim to partner with.
He is a great defender on the ground,fast,good on the ball and would be a great signing for a top team which already is great and would give even more quality but missing some important attributes we need in our defence and would consider for 70m max but anything higher not a chance.
We need a towering centre back,great at heading,comfortable on the ball but mainly a Chris Smalling upgrade because he cant pass the ball and we suffer in building attack from the back and that is what modern football is all about.
Maguire is a better option to what we need even if Koulibaly is a better player all-round but also Maguire asking price isnt probably low but a better option for certainly and used to Premier League.
Younger options that could fit the bill:Andersen,Tah or really young Saliba and maybe Zagadou,Milenkovic.