Clrnc
Rico Lewis is 19, Nwaneri and Skelly are 16. Lewis is also very good, I'd wager he'd get at least comparable mins here.
Secondly, if Walters came into a title challenging side, he'd be playing with what is already the youngest squad in the league, one that's not won anything, not treble winners and winners of 3 consecutive league titles.
Lastly, when 18yr old Lewis came in last year City ended up 8 points behind us. Barely played a min in their run in. He played Lewis because he had no other full backs to speak of, they were playing Bernardo Silva at left back. Eventually Pep just decided he's better off playing 4 centre backs.