Forgive me if I've got ratings on the brain. With the BCS prominently in the news, I've been thinking about how teams rank. Naturally, in the NBA this isn't usually a big deal. For one thing, we have a playoff system that probably does the best job of any of the major sports of crowning the league's best team as champion. For another, by year's end schedules have largely evened out--conference imbalance aside--meaning that with the exception of the issues we statistical analysts raise with regards to point differential, records can be compared on a level playing field.
A little over a month into the season, neither of those factors quite applies. We're months away from the playoffs, and schedules are still uneven, especially when it comes to home/road differential. The Charlotte Bobcats have played 14 of their 20 games at home, while the Portland Trail Blazers have been on the road 15 times in 22 games, which makes their 15-7 start especially impressive.
If there were an NBA BCS, it would face a challenging task picking between the three contenders who have separated themselves from the pack:
- The Boston Celtics, last year's NBA champions and owners of the league's best record at 20-2 courtesy a 12-game winning streak.
- The defending Western Conference champion Los Angeles Lakers, 17-2 thanks to an improved defense.
- The 17-3 Cleveland Cavaliers, who have revitalized their offense, which now ranks tops in the NBA to go with a defense that ranks second.
Let's take a deeper look at the three contenders for the ceremonial title of league's best team through the first 20 games, using a variety of metrics and rankings that I'll explain as we go.
Offensive/Defensive Ratings: 106.2 (8th)/98.9 (1st)
Differential: +9.2 (3rd)
Adjusted Bell Curve: .827 (3rd)
Prospectus Hoops List: 65.2 (3rd)
SRS: 9.14 (3rd)
Hollinger Ranking: 110.0 (3rd)
A year ago, the Celtics' 20-2 run to start the season stamped them as contenders and presaged their eventual run to the NBA title. Who would have figured Boston would duplicate the hot start even after losing key role players James Posey and P.J. Brown? With Sunday's win at Milwaukee--their 12th straight--the Celtics have done just that. Already in Boston, talk has begun to turn to whether this year's Boston team might be stronger than the champs. That seems a little premature.
While the Celtics boast the same record they did a year ago, their performance has not been as impressive. Through 22 games in 2007-08, Boston had outscored teams by a remarkable 14.2 points per game. As well as they've played, none of this year's top three teams can match that kind of dominance. Eight of the Celtics' 20 wins then came by 20-plus points; compare that to just one win by 20 points so far this season.
The good news for Boston in the long term is that part of the difference can be attributed to Doc Rivers showing more faith in his bench this year even without Posey. Tony Allen, freed from point-guard responsibilities, has stepped capably into Posey's role of wing stopper off the bench, while Brian Scalabrine has seen additional action. This time a year ago, Ray Allen was averaging nearly 39 minutes a night, Paul Pierce 38 and Kevin Garnett 35-plus. Those numbers are down to 35.8, 36.9 and 33.1 respectively this year. A fresher "Big Three"--which really should be the Big Four this year, since Rajon Rondo has been as valuable as any of the Celtics' veteran stars--will be an asset in the postseason.
No matter the ranking, Boston comes up short compared to this year's other two top contenders. The most favorable metric is the Bell Curve method pioneered by Dean Oliver, which uses the distribution of a team's scores to estimate its odds of winning any single game. Adjusted for home court but not for schedule, this moves the Celtics closer to the other two teams because Boston's wins have been by more consistent margins in the mid-teens. Through 22 games last year, the Celtics had a dazzling .923 adjusted Bell Curve winning percentage, far better than any of the three teams have posted this season.
Offensive/Defensive Ratings: 111.8 (1st)/99.9 (2nd)
Differential: +13.3 (1st)
Adjusted Bell Curve: .868 (1st)
Prospectus Hoops List: 68.7 (1st)
SRS: 13.11 (1st)
Hollinger Ranking: 114.5 (1st)
If we are to consider these rankings the equivalent to the computer portion of the BCS, the Cavaliers are your clear No. 1 team right now. What is most impressive is the unanimity of the rankings. I intentionally chose a variety of different measures. The Adjusted Bell Curve method does not consider schedule, while Basketball-Reference.com's Simple Rating System (SRS) pays no attention to whether games are played at home or on the road. The Prospectus Hoops List is unique in that it does not incorporate point differential. No matter how you look at it, the Cavaliers are atop the league. John Hollinger's power rankings end up the most favorable because they weight recent performance more heavily and Cleveland has been on fire of late, winning eight straight games by double-digits.
Like most everyone else, I figured the addition of point guard Mo Williams would improve the Cavaliers' offense. I'm not sure anyone suspected Cleveland would boast the league's best Offensive Rating a fourth of the way through the season. Last year, the Cavaliers were 1.5 percent worse than league average on offense; this year they're 8.1 percent better. Only two teams in the last quarter-century have made bigger jumps (the 2003-04 Denver Nuggets, who added Carmelo Anthony and Andre Miller to a team that had been essentially tanking the previous year, and the 2004-05 Phoenix Suns, who added some point guard named Steve Nash).
Surely the addition of Williams has been a big factor, and our own Anthony Macri broke down how Cleveland has taken better advantage of LeBron James' skills this season. Still, the offense strikes me as a tad bit fluky. Zydrunas Ilgauskas is shooting a career-best 53.2 percent from the field thus far, up from 47.4 percent a year ago, and I'm dubious he can keep shooting quite that accurately at age 33. Delonte West is another Cavaliers player shooting well better than his career marks in the early going who may cool off.
Overshadowed by the strong offense is that Cleveland is also defending better than ever. Mike Brown has focused on the defensive end of the floor and the Cavaliers were fourth in the league in Defensive Rating two years ago, when they went to the NBA Finals. Last year, their defense slipped all the way to 11th. Brown's charges are locked in defensively once again, which is more likely to hold up over the course of the season.
Los Angeles Lakers
Offensive/Defensive Ratings: 110.1 (2nd)/100.9 (3rd)
Differential: +12.2 (2nd)
Adjusted Bell Curve: .850 (2nd)
Prospectus Hoops List: 67.2 (2nd)
SRS: 12.14 (2nd)
Hollinger Ranking: 111.0 (2nd)
As recently as a week ago, I was all ready to anoint the Lakers the favorites. In hindsight, that was premature. The Lakers' road trip wasn't exactly a bad one--L.A. went 2-1, losing only on a game-winning putback--but nor was it as impressive as the start that had Lakers fans thinking about making a run at the 1995-96 Chicago Bulls' 72-10 record.
In late November, Neil Paine of the must-read Basketball-Reference.com Blog noted that the Lakers were posting the fourth-best opening-month SRS of any team in NBA history. Here's a case where looking at only one metric can be misleading. SRS, as mentioned, does not account for game location. That inevitably boosted a Lakers team that played 10 of its first 15 games at home. Predictably, the Lakers lost a little luster when they made their first trip back East.
(Neil's research does also brings up another important point about the danger of extrapolating from a fast start. The list of hot-starting teams is littered with NBA champions, virtually all of whom fell off from their early pace. So while it's noteworthy that the Cavaliers currently surpass the '95-'96 Bulls in terms of point differential (+12.2) and the Lakers have matched them, don't get too excited about a historic season just yet.)
While the Lakers' start can't quite compare to what Cleveland has done, it has been impressive. Maybe it's as simple as the fact that the Lakers' success was more predictable going into the season, but it feels more sustainable. In their favor, subjectively, is the presence on the sidelines of Phil Jackson, who has more experience than any living coach in terms of managing a championship contender over the course of the season and having that squad peak at the right time. Also, the only Lakers player substantially exceeding expectations and career norms is Trevor Ariza.
The Lakers' defense has slipped a little and is now the worst of the top three contenders (take note, ultra-literal "defense wins championships" believers!). That seems reasonable as teams have had more opportunity to adjust to their unorthodox system. The Lakers don't need to have the league's best defense to win a championship; remaining in the top three is a reasonable goal and gives them more than enough balance.
There are plenty of Western Conference foes that can point to early-season injuries and expect to give the Lakers a run come springtime. San Antonio has surpassed my dire predictions for the first month of the season sans Manu Ginobili, Utah is in the mix in the Northwest Division despite being beset by injury, Houston still hasn't gotten a chance to jell because of its own health issues. It's yet another team, Portland, that ranks by most of these metrics as the biggest threat to the Lakers in the early going. Nonetheless, it will be tough for any of those teams to catch them for home-court advantage, and the Lakers continue to look like the class of the West.
The East is not so simple, at least beyond saying that right now it looks like an epic Eastern Conference Finals slugfest between the Celtics and Cavaliers. Who would I take from the East in an NBA BCS? Cleveland is the choice on past performance, but I suspect Boston will ultimately narrow the gap. I feel like our friend Nate Silver did last week discussing a political race on fivethirtyeight.com when he concluded, "If you put a gun to my head and asked me to predict the winner, I would tell you to shoot me." Fortunately, the NBA requires us to make no such choice, and Boston and Cleveland will presumably vie for East superiority on the court instead of in the power rankings.
Kevin Pelton is an author of Basketball Prospectus.
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