The way that you worded the subject made me think that the stats were a landslide, when they're actually pretty close. LA edges out Boston in several stats, especially rebounds. Boston takes the statistical win here, but not by much. While the East seems to have the most elite teams, the West is overall a much stronger conference, so Boston's team stats should be better than LA's anyway.
If you want statistical team rankings, just check out Hollinger's Power Rankings. Sometimes his rankings don't tell the whole story, but here they're are right on the money, with Boston having the slight edge over LA.
http://espn.go.com/nba/hollinger/powerrankings
To me the Rebounding is way over blown. The lakers get 2 more rebounds a game, but If you think about it the C's are a much more efficient offense which mean there are going to be fewer chances for offensive rebounds. The C's are actually # 6 in opponent rebounding , while the Lakers are # 24. That is the real stat you should look at for rebounding because like I said the C's are much more efficient shooting 3% higher.
The C's are also # 10 in OPP Offensive rebounds allowing 10.9 per game while the Lakers are ranked # 29 alloing 12.9. The C's aren't letting the opposing team get 2nd and 3rd chances to score .
A couple of quick thoughts:
Regarding the Celtics being the "much more efficient offense," entering Sunday, they averaged 0.8 more points per 100 possessions than the Lakers, out-ranking LA 9 to 10 in offensive efficiency across the league.
As far as your rebounding numbers are concerned, using flat rebound figures is flawed because it doesn't account for pace. Teams that play at higher paces play games with more possessions, which means more shots taken, which likely means more missed shots, which means more rebound opportunities. All of that is to say that rebound rate figures paint a more accurate picture: In this case, yes, the Celtics are better on the defensive glass, but not by as wide a gap: they rank 13th to the Lakers' 19th in protecting the defensive glass.
Further, the use of offensive rebound rate instead of flat offensive rebounds accounts for your claim above about the issue of opportunities. And that indicates that the Celtics have been horrific on the offensive glass this year, ranking 29th to the Lakers' 10th in offensive rebound rate.
In a similar vein, in the name of accounting for pace, for the statistics breakdown in your OP, I think you'd get a lot more out of an evaluation conducted using points scored and allowed per 100 possessions (offensive and defensive efficiency) and turnover rate rather than points scored/allowed and turnovers per game.
-sw