Ive watched it several times, Winks and Eriksen are in the centre, there is no Chelsea players anywhere near them and three Spurs defenders against two Chelsea players initially, Winks gets back and makes an extra body in the centre of the area, meanwhile Kante is starting to make a move forwards to give them another option (and it is him that eventually gets on the ball, and Dier was actually jogging with him and can see he's the only other real threat, but somehow just lets him stay in front of him and eventually receive the ball.
You can say Eriksen could have run back as well but once he sees Winks is, he figures 4 v 2 should be plenty - not ultra diligent but then he's not ultra defensively diligent - no one claims he is, he's got a shit load of other qualities he brings - and we all Know Winks has learning to do but he's definitely improving the defensive side of his game and at least can move quickly - but Dier is there purely for his defensive qualities, no other reason, that's my issue, if he's not doing them very well, and I've never thought he's very good defensively, he's too slow and cumbersome, then what's his real value.
Also the issue at the corners. First the one they score from, he was doing nothing, marking no one, but still didn't pick up the fact that two players were stood on the D waiting to pick up loose balls. I'm disappointed that TA and JV didn't shout this out either, but they were busier marking and jostling, Dier was just stood doing nothing and then when Kante shoots Dier kind of flinches from the block too.
I like him as a CB, I think he's actually ahead of where TA was in his development curve (if you think about how TA couldn't get a game at CB for AM, was shunted around and ended up on loan at a mid table PL club) and could be the ready made replacement at CB, but I hate watching him in midfield, there was a point last night where he got the ball in their half, we we had a bit of possession, he had two options forwards to his left calling for a pass, but he's got no game picture in his brain, and when he hasn't got this game picture of what's around him, he is also incapable of taking it on the turn, buying himself some time and then looking forwards (like Winks has been doing), he just whacked it straight back about 30 yards to JV. He's ponderous, cumbersome, slow, too easy to turn without the ball, and take out the game.