Oh come on, wake up, Dion isn't that good defensively!!! If we had a top shut down D paired with him, we win game 7!
He's a hell lot better than Karlsson, Letang and Subban defensively, though. In fact, the only way I could see him take tough defensive assignments at high minutes is if he could move the puck like those offensive defenceman. That's an aspect one could attack considering his puck moving ability isn't elite like say, Tomas Kaberle.
Chara, in fact, would struggle in this role. He tends to make a lot of mistakes if expected to do everything. Since he has Boychuk who, at the moment, is taking the toughest assignments amongst D while making effective first pass. In addition, there is Ference who takes very tough minutes as well playing defensively. In that situation, one can give Chara that big minutes, Boston has a lot of specialists.
Furthermore, the lack of consistent puck support from the forwards is what our defence. I am still puzzled on why that's barely mentioned on these boards, because that's why we ended hemmed in our zone. In fact, our forwards were wandering off too much, while in Boston, we see a more cohesive unit. Then again, they have defensively strong centres (outside of Krecji who is a bit above-avg) who can be planted in the defensive zone and yet keep the puck in the offensive zone. The only two centres who can do that on our team is Grabovski and McClement, and latter is not much of an offensive threat.
