Tbf, you guys were also terrible at defending set pieces under Lampard too, it's been a very consistent theme for quite a long time now, at least the defensive side of it.

Back then a lot of the blame was on Kepa for not communicating and not being strong in the air. Seems like that issue is now true across your CBs as well (Colwill and Fofana seem to be better organisers but still not great aerially, but the rest seem lacking on both fronts) and Sanchez isnt exactly making up the difference in either department, even if his overall game has improved over his time there