What has Koulibaly really won in all that time compared to Dias? Experience and league he plays in is obviously better to Liga NOS, and he's the better player; but let's say this season goes wrong, his signing would have been a bigger disaster. The age factor is massive. This is smarter business considering comparative factors of having the two. Immediate impact and title challenge maybe would've been looking better but, no guarantees.well obviously for a 6 year stint, but if we want to challenge today it’s Koulibaly all the way for me.