There are some big issues there IMO.
The stats don't really take into account the really different situations a d-man is exiting the zone. For example these two situations differ HUGELY: 1) Your team regains the possession down-low, the player getting the puck breaks the pressure by successfully passing it to the other side of the rink to a open d-man who can start the rush with plenty of time and space and 2) a d-man breaks the possession himself, battles his way out of the corner to the center ice and starts a quick rush by dishing the puck to a open forward and supports the rush himself.
The latter situation is FAR MORE demanding, and it usually gives your team a good scoring chance by generating an odd man rush (because usually there are only two defenders at max). The first situation is a lot more easier, and usually the player with more puck skills is the player who is the guy who starts the rush in that situation (because you got enough time to get the guys on their proper places).. I think this, partly, explains the difference between Josi and Weber regarding those stats. The problem with the first situation is that even though you get out of your own zone far more easier, you usually face an organized unit, and generating a quality scoring chance is difficult.
Cody Franson is extremely good at clearing the zone in former situations (outside of occasional grenades), but he is really bad in latter situations.
And what comes to the Polak situation. I do believe that most coaches instruct certain players to play in a certain way. For example I think DeBoer prefers Polak doing what he did despite his team losing the possession. In general your team mates should have a pretty clear idea what a certain player is going to do with the puck. For example in the Polak situation teammates have to know that is he going to just clear the zone or play it to his teammates by making a reversal pass. The game is so fast that you simply cannot wait and see - you have to know in advance.
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And I agree with the poster who said that breaking the opponent's possession is almost equally important here (and how you break it matters in what kind of situation you start the rush as a defenseman). Players like Pysyk and Fowler are not exactly good players breaking the possession down-low/corner, but they're good players when the team gets the puck. And the importance of being able to break the possession is perhaps the biggest reason why we should be patient with Bogosian. When he is on, he can alone break possession by just bulldozing even the bigger forwards in the corner. In the playoffs, when more and more plays are played down-low and in the corner, the value of a skill like that is extremely high.