Last week, I was struck by a pair of otherwise unrelated NBA columns that drew the same conclusion: In the wake of the Boston Celtics winning the NBA championship, teams around the league have made defense a priority in the 2008-09 season.
First, I read Bill Simmons' NBA "reps" column, in which the Sports Guy made the following one of his observations about the early season:
8. What the heck happened to scoring?
Through four weeks, the games themselves have been lacking in the entertainment department and I couldn't figure out why. Then I checked the scoring.
[...] That's right, we're drifting away from the "Scoring Is fun!" era.
Steve Aschburner of SI.com took the analysis a step further, using advanced statistics. It was highly encouraging to see a mainstream columnist cite Dean Oliver and use Defensive Ratings and effective field-goal percentage.
OK, so...where does the NBA stand, defensively, at the moment? Through Monday, three teams--the Lakers, Celtics and Magic--had defensive ratings below 100 ("below" is a good thing, remember) and a total of 15 were limiting foes to 105 points or fewer per every 100 possessions. The comparable numbers from last season: one team (Boston) below 100 and just four below 105.
Aschburner wisely offered the caveat that the sample size remains small a month into the season. Unfortunately, he and Simmons both missed a larger point that trips up their analysis. Namely, offense tends to pick up as the season goes on, and teams historically struggle offensively in the month of November as they get comfortable with each other and the playbook and get back into a shooting rhythm.
I've been aware of this trend for some time, but never had the numbers to quantify it. Fortunately, my partner in crime, Bradford Doolittle, was able to pull month-by-month numbers from his 2007-08 database. Let's take a look at what they show.
Month Rtg Pace PPG eFG% OR% FTA/FGA TO%
Oct/Nov. 107.1 91.5 98.6 .490 .262 .317 .137
Dec. 107.8 90.9 98.6 .491 .268 .313 .134
Jan. 108.4 90.4 98.8 .493 .268 .310 .132
Feb. 108.9 90.4 99.2 .494 .268 .309 .131
March 109.7 90.4 99.8 .497 .268 .308 .128
April 109.8 90.4 99.9 .497 .267 .306 .128
Offensive Ratings improved each month before peaking in April at just shy of 110--a difference of nearly three points per 100 possessions as compared to October and November games. At the micro level, in terms of the Four Factors, there are also some clear trends. Shooting improved slightly over the course of the season, while teams also progressively improved in terms of taking care of the basketball. The only advantage offenses have in the early going makes some sense--defenses are more prone to sending them to the free-throw line, which could be another effect of rust.
For another way to look at the issue, poster Cherokee_ACB on the APBRmetrics message board created this day-by-day chart for Offensive Rating throughout the 2005-06 season.
No matter how you conduct the analysis, it is evident that a comparison between offensive performance over the first month of the season and a full year is going to paint a misleading picture. That being the case, let's compare October/November 2008 to October/November 2007 and see whether it is really fair to say offense is down around the league.
Year Rtg Pace PPG eFG% OR% FTA/FGA TO%
2007-08 107.1 91.5 98.6 .490 .262 .317 .137
2008-09 107.5 90.7 98.1 .489 .270 .311 .138
(Note that this year's numbers are through Tuesday, so they do include two days' worth of December stats. The effect should be negligible.)
From this perspective, it appears that any talk of a renewed trend toward defense in the NBA is inaccurate. The shooting and turnover numbers are virtually the same as they were a year ago, with improved offensive rebounding more than canceling out the fact that there are fewer free throws being shot in the early going.
Where Simmons might be on to something is that the pace has in fact slowed a bit in the early going. Last year, games were played at a higher pace in November than they were the rest of the season, slowing again after December before settling in at 90.4 possessions per 48 minutes. So far this year, teams have played only slightly faster than that.
To dig a little deeper, I compared each team's pace so far this season to their pace from 2007-08. What's interesting is that the median change is none at all. Essentially half of teams are playing faster and half are playing slower (note that this isn't quite as odd as it seems because we're comparing the first month to the full year, when things were slower; I don't have team-by-team numbers for November 2007).
The slowing, then, is apparently due to the fact that while five teams are playing at least two possessions faster per 48 minutes--all of them, in something less than a coincidence, featuring new coaches--a whopping nine have slowed their pace at least that much. The biggest changes:
Team 0708 0809 Diff Team 0708 0809 Diff
NYK 90.3 96.9 +6.6 DEN 98.2 93.3 -4.9
DAL 88.8 92.2 +3.4 PHO 95.1 90.3 -4.8
WAS 88.3 90.5 +2.2 CHA 90.3 86.7 -3.6
DET 86.3 88.4 +2.1 MEM 93.6 90.7 -2.9
CHI 91.9 93.9 +2.0 SAC 93.3 90.8 -2.5
UTA 91.8 89.5 -2.3
IND 96.1 94.0 -2.1
OKC 95.0 92.9 -2.1
NOH 88.4 86.4 -2.0
While no returning coaches have seen fit to push the tempo, a number have sought to slow things down. What is especially noteworthy is that the list includes three second-year coaches who had relatively fast-paced teams in their first year at the helm of new teams--Marc Iavaroni, Jim O'Brien and Reggie Theus. Meanwhile, it's a veteran coach, George Karl, who has slowed things down the most with positive results thus far.
It's a little too early to describe this as a trend, but it's possible the league may be slowing down slightly. That doesn't mean that teams have embraced defense any more or any less than they did a year ago.
Kevin Pelton is an author of Basketball Prospectus.
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