Northwest vs Southeast Division 2005-10

There seems to be some incredulity about my statement that on the basis of their negative shot differential in head-to-head games, the NW division teams have not been better than the SE division teams.  How can this be possible if, in 107 head-to-head games, the NW has a .570 winning percentage?

Well, it all comes down to unsustainable and uncharacteristic save and shooting percentages:

Both divisions played 2050 games over five seasons and ended up with roughly the same save and shooting percentages over all of those games.  But in 100 head-to-head games in the regular season, the southeast division shot just 4.16% (and the northwest division got a 958 save percentage).  Those rates have no relationship with the teams' true talent levels observed over thousands of games, but it is possible to sample 100 games where we see uncharacteristic percentages.  In other words, sometimes strange things happen – but it doesn't mean that the NW division is better than the SE division.

Here's the division-vs-division PDO grid with the NW-SE pairs in bold:

And the composite PDO, Sv% and Sh% for each team against other divisions since 2005:

There is something real here – SE shooting percentage is 0.4% lower than the league-wide average (goaltending is exactly average.)  But there's no reason to expect them to have a 979 PDO against the NW.