Not quite that simple. It's not just that they play in the SE division, it's that you get 4 more games against those teams than any of the other teams from other divisions. It's more than just the results, too, it's how easily you're able to get them. If the Caps played out this season 5 times in parallel universes, lol, those numbers for the NE and Atl. could change a lot each time. Games against Carolina aside, Washington had a much easier time dispatching divisional opponents compared to other opponents (outscored Atlanta, TB and Florida combined 82-45 in those games, versus 236-188, or, to reduce/simplify the fraction/ratio, 118-94 or 59-47 against the rest of the teams).
I think that goal margin is proportionally double, suggesting the Caps could beat their division rivals (at least slightly) more comfortably and consistently than the other teams. In an 82 game schedule, I have to think that's at least a small factor. Instead of just 1 or 2 points, it could work out to 5 or more depending.
Not to mention 4 of the bottom 6 (NYI and TOR other 2) had the worst goals against in the east... I wonder why?