He's the one who isnt alert and moving. Ander is taking care of the outside of the box and gets physical with the player to impede his run on the first ball. After that he's not with the player, he's taking care of the outside of the box.
Our CBs set up to the right of the rest of our players in the box, in a line, they werent marking anyone. Lindelof especially was there on his own with Jones slightly closer to the player who beats Pogba to the first header. Lindelof and Jones are marking space not players and those are our CBs.
Looking at it again its another ball thats dropping inside De Gea's 6 yard box. There are definitely keepers who would have come out to put pressure on the player or tried to claim it