I think one of the issues with our defence, which is why we are so weak to an over the top ball is some centre backs are not good in the air, I've watched the Palace game , Juve game other highlights from last season.
Dias and Akanji are not good at aerial battles, Gvardiol stats he is better at dealing with over the top balls and aerial challenges, Noticed when the camera pans to Pep he looks so frustrated he starts shouting at the defence. Because its something that Pep can't do anything about.
Genuinely Dias and Akanji for their height lose so many aerial challenges. Juve game in particular they play a ball over the top from their keeper and both centre backs go for the ball and miss it giving Vlahovic a 1v1 against Ederson.
Stats back it up
Akanji only wins 17 percent of his aerial duels
Dias wins 11 percent of his Aerials duels
Stones wins 84 percent of his aerial duels
Ake wins 50 percent of Aerial duels
Gvardiol 77 percent of Aerial duels.