The chart plots points allowed per hundred possessions relative to the league median. The very worst teams in the league -- New York and Minnesota -- both allow 5.7 more points per hundred than the median. Boston, by contrast, allows 5.5 fewer points per hundred than does the next best team. In short, not only is Boston the best, but the gap between the best and the second best is enormous. They're leaving everyone else dead in the water.
Boston is averaging 101.7 points per game, while giving up 87.7. You'll win a lot of games that way.
You might be wondering where Dallas, with their formerly vaunted defense, is on that chart. Try seventh...from the bottom. I was starting to come around to the theory that the Mavs were so mediocre in the regular season thus far because they weren't going crazy about regular season losses, were trying to keep minutes for starters low (an approach Avery Johnson is close to ditching) were trying to get their rotation together, etc., etc. But I'm beginning to think that's just salve for the psychic wound in my mind that I've developed as a result of watching the Mavs go 14-9 and eke out wins over the Stephon Marbury-less Knicks or scoring a season-low 76 points against the mediocre Toronto Raptors. Supposedly Avery Johnson is getting ready to have it out with his team for their lackluster, confused and highly inconsistent performances. I say, bring it on. Maybe a full-on behind-closed-doors chair-throwing temper tantrum is what is necessary to put some fear back into this team, because consistent embarrassment on the court is obviously not doing it.