Lampard essentially ruined a back line that already built some sort of understanding. He created unbalance by shoe horning Dave at LB just because he wears the arm band. He then dropped Tomori for god knows why, for Christensen because 'Morris rates him'. All at the same time, taking Zouma, who is very suspect positionally, to play on the other side. Something Rio Ferdinand even said he had a difficult time doing.
That's what lost us the game, and it was bloody amateur from Lampard. I would fucking hope he learns from this calamity.