Your not objective at all then mate. Of course he dives, so does Sterling, so does Salah, Ronaldo has done it all his career... A couple of months from now it’s very likely his fellow premier league footballers are going to vote him as being the best player in the league this season. They all clowns too? 35 goals from centre midfield since last February, with loads of assists on top would suggest not. That’s not my personal view as for me it should be Dias but it’s what I think will happen.
Would I take him as part of our squad, absolutely. Would he fit into the same 11 as KDB, probably not, would be a bit like Gerrard and Lampard imo in that you wouldn’t get the full benefit of one of them if you tried to accommodate both.
To answer your other question, world class to me is being one of a small number of players who are the best in the world in their position and who would not look out of place in a world 11.
KDB - world class
Mahrez - very good but not world class
Bernardo - for me his work rate combined with his talent make him world class when he’s at his best
Peak Fernandinho - world class
Cancelo - based specifically on this seasons form, world class
Foden - Very good and will undoubtedly become world class.