Your second picture shows both guys on the right side below the goal line.
Miller was out of position in the 1st pic. Defenders should NOT be chasing guys to the off side.
It was a poor decision by Miller. I actually found that he chased a few times last night, this one happend to burn them.
The good thing in all of this is that it can be corrected.
But he has to stop chasing and stay in his lane.
Less is more here
He didn't chase the guy to that side, just watch the replay, damn.
There was a scrum for the puck along the right side boards, when it came out, Trouba was in a position to chase the puck to the left corner to pick it up and break it out. That's when Trouba and Miller "switched". Basically they just never went back over to their respective sides. When the Habs brought the puck back in over the blueline, Miller was on the right and Trouba on the left. The Habs got the puck back up the ice fast enough that the D didn't get back over to their normal sides, so the guy breaking in on the right side of the ice was Miller's guy now, he was in position for that. He kept the guy wide, went for a poke check that didn't connect but the player was still forced behind the net. Here's where it got tricky, because Trouba tied up the Habs player going to the front of the net but they both went past the net a bit and a shove from Trouba sent the Habs player into Millers path, which means Miller got picked. Meanwhile McKegg is floating in the slot watching the play, then tries to attack the puck carrier as he comes around the net, which leaves the slot and Drouin wide open for the easy player. Trouba and Miller were still tied up and couldn't get back to the slot.
Trouba and McKegg are more to blame. Miller could have tried to release from his player and cut around the front of the net instead, but Trouba was tied up and there was no way for them to switch that coverage at that point. McKegg could have held his position in the slot but instead went after the puck carrier, and no one else got there in time to cover the slot.
If I'm going to fault Miller for something it's that he probably needed to play his gap better and force that forward back or into the boards rather than missing the pokecheck and then trying to force him around behind the net. That's when things broke down when Trouba shoved his guy into Miller while trying to tie him up.
But the big point here is that Miller didn't chase his guy to the wrong side of the ice and if you actually watch the replay you'll see that