Two years ago the Houston Rockets posted a 5.2 efficiency differential (offensive efficiency minus defensive efficiency), won 52 games, and were bounced in the first round of the 2007 playoffs. Last year the Rockets won 55 games with a 5.0 efficiency differential, and again the team lost in the first round.
After two “good” seasons that weren’t “good” enough, the Rockets made a move that was designed to transform Houston into a legitimate title contender. Last August the Rockets sent three players to the Sacramento Kings for Ron Artest. Here is how the move was described by John Hollinger, J.A. Adande, and Ron Artest:
John Hollinger (Artest makes it a trio, boosting the Rockets’ offense, title hopes):
The big idea is that Artest, between his scoring and his underrated playmaking skills, will add enough offense to get Houston well into the upper half of the league in offensive efficiency. From there, the Rockets’ suffocating D – with Artest adding yet another stopper to the mix – can accomplish the rest. If it comes to fruition, Houston could find itself hoisting the Larry O’Brien Trophy next June.
J.A. Adande (From the edge, Artest gives Rockets a missing element):
Go ahead and group the Rockets with the Hornets and Spurs – not just because they’re in the same division, but because they can legitimately challenge the Lakers for their Western Conference crown.
Ron Artest (Rockets agree to send pick, Greene, Jackson to Kings for Artest):
“Boston kind of blitzed the whole league with that trio they have. To pretty much compete for a championship, you need a trio and some great role players. I guess if it’s McGrady, Yao and Artest … I’ll let everybody else do the math.”
Rockets Math
Last summer I did some math and concluded that this move really didn’t make the Rockets much better. Now that the Rockets have played 32 games this season, we can do even more math. And again, it’s hard to see how the Rockets are now championship contenders.
In 2007-08 the Rockets scored 103.7 points per 100 possessions while allowing 98.6. This season the Rockets are scoring 104.0 points per 100 possessions while allowing 100.1. So their offensive efficiency is about the same while their defense has worsened a bit. Consequently, their efficiency differential has declined to 3.9. In simple words, Houston is not quite what the team was last year.
When we look at the performance of Houston’s players we see can trace the team’s small decline to specific individuals.
Table One: The Houston Rockets after 32 games in 2008-09
Specifically – as Table One indicates — Brent Barry, Carl Landry, and Chuck Hayes are offering less in 2008-09. If these players – and the others employed by Houston — maintained their 2007-08 production this team could be on pace to win 58 games. Such a mark is consistent with an efficiency differential of about 6.8.
Currently the three teams who are serious contenders for the 2009 championship have the following differentials (as of Monday night):
Cleveland Cavaliers: 13.6 efficiency differential
Boston Celtics: 11.3 efficiency differential
LA Lakers: 9.9 efficiency differential
So even if Houston’s players were doing what they did in 2007-08, the Rockets would still lag far behind the real contenders.
What of Artest?
Entering this season Artest had played 18,587 minutes, produced 41.0 wins, and posted a 0.106 WP48 [Wins Produced per 48 minutes]. In his best season – in 2006-07 with the Sacramento Kings – he played 2,641 minutes, produced 8.6 wins, and posted a 0.156 WP48. In sum, Artest is capable of exceeding the average mark of 0.100, but he has not demonstrated the ability to move very far beyond the productivity of an average NBA player. Such numbers suggest that Artest is not a player who is going to substantially change outcomes in Houston. And now that he’s coming off the bench, it appears the coaching staff in Houston might have concluded that although Artest can make a positive contribution to a team’s success, he’s not quite the key player people thought he was last summer.
Houston Keys
If we look back at Table One we can see the most productive players – or the key players – on this team. Topping the list is Yao Ming and Tracy McGrady. Ming is essentially the same player he was last year. T-Mac – after his worst season as a professional in 2007-08 – has essentially returned to what we saw in 2006-07. He’s still not the player he was in Orlando or Toronto. If he can stay on the court, though, he could get to double figures in wins.
After the contribution of the two major stars on this team, we see Luis Scola and Carl Landry. These two players have combined to produce 5.0 wins this year in only 1,555 minutes. To put that in perspective, Artest, Rafer Alston and Aaron Brooks have played 2,599 minutes this season and have also combined to produce 5.0 wins. In sum, the strength of this team is at center, power forward, and T-Mac.
To this strength the Rockets are adding Dikembe Mutombo. Across the past four seasons Mutombo has produced 25.1 wins in only 4,076 minutes [for a 0.220 WP48]. As has been detailed before [see The Surprising Mount Mutombo] Mutombo is more than capable of filling in for Yao if (or when) he again misses a significant portion of the season.
Relative Performance
Even with Mutombo, though, the Rockets will probably not close the gap between them and the Lakers. Houston, though, is still capable of competing with the other top teams in the West. Currently there are seven teams with an efficiency differential between 3.0 and 4.4 in the Western Conference (Portland, Houston, New Orleans, San Antonio, Utah, Denver, and Dallas). So at the moment, Houston could be the second best team in the West (or they could be the eighth best team).
Last year Houston’s differential of 5.02 was only the 6th best mark in the West. Hence it was not surprising when they lost in the first round of the playoffs. Currently, though, the Rockets have the third best mark and might be favored in the first round in 2009 (if these numbers hold up).
It’s important to note, though, that this is not because Houston has built a better roster. No, the improvement we see in Houston’s standing is due to other teams in the West declining.
In sum, Houston’s relative position has improved. But this is not about the addition of Artest or any other change Houston has made. No, the answer to Rockets relative improvement in the standings (but not improvement in efficiency differential) is found outside of Houston.
– DJ
The WoW Journal Comments Policy
Our research on the NBA was summarized HERE.
The Technical Notes at wagesofwins.com provides substantially more information on the published research behind Wins Produced and Win Score
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Simple Models of Player Performance
What Wins Produced Says and What It Does Not Say
Introducing PAWSmin — and a Defense of Box Score Statistics
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.
Wages of Wins Journal 
TRad
December 31, 2008
Thanks, David.
That’s what I was thinking – that Artest hasn’t improved the Rockets and that Hornets/Suns/Spurs/Jazz are a little worse than last season.
Who could imagine before the season that three of the four best teams would play in the East?
Michael
December 31, 2008
Professor,
I was wondering if you use the PAWS method to calculate wins produced, are the total wins produced for each team a useable statistic? Or is it too inaccurate? I found that for some teams the total was exactly the same as the number of games they had actually won, but for others it was quite inaccurate (such as the Thunder, who apparently have produced 11 wins but only won 3 games)
Anyway using the total number of wins produced here are the rankings for the teams you mention:
Denver: 26.45
Utah: 24.35
Houston: 23.14
Portland: 22.92
Dallas: 21.85
San Antonio: 20.73
New Orleans: 17.24
Whether or not this ranking is useful is another story!
dberri
December 31, 2008
Michael,
PAWSmin is a good approximation of WP48. But PAWS is not as good an estimate of Wins Produced. To calculate Wins Produced you need to take into account team defense. This issue is addressed on the links I posted.
Vince G.
December 31, 2008
At the end of the day, the summation of the wins produced in either formula must be as close to the number of games as possible, since each game has 1 winning team and 1 losing one.
Italian Stallion
December 31, 2008
Doesn’t any analysis of Houston have to more less be taken with a grain of salt because of the chronic injuries to Yao and Tracy in recent years?
It seems to me Houston’s prospects are very correlated to amount of time their 3 major players spend on the court together.
Vince G.
January 1, 2009
I.S.:
Even without Wins Produced, Houston (during McGrady’s tenure) has won about twice as many games percentage-wise when McGrady is on the floor than without him.
During the Rockets’ last three seasons (When Yao has been injuried the most), their regular-season record without Yao has been:
2005-06: 7-18
2006-07: 20-14
2007-08: 19-8
Combined, they’ve won 53.4% of those games without him, and 59.4% of games with him.
No comment on the ascending winning percentage in successive Yao-less seasons.
mrparker
January 1, 2009
stalion,
Hasnt houston gone on its major win streaks with yao out of the lineup
Michael
January 1, 2009
Without seeming flippant I’d like to add that the prospects of any team are highly correlated to the amount of time their 3 major players spend on the court together!
Italian Stallion
January 1, 2009
My feeling is simply that it gets very difficut to weigh and measure the impact of individual players on a team and how that team stacks up against others in the league until you have a large enough sample of them all being healthy at the same time and playing at their current level of ability together. Houston is almost never in that position.
Vince Gagliano
January 1, 2009
Yeah, even without injury-prone stars, it can still be difficult to assess an individual player’s total impact on a team. Dave’s mathematical model is just that, a model for trying to describe that productivity using stats.
For example, Gilbert Arenas and Brandon Haywood are essentially average players according to Dave’s model. So why has losing them put such a huge dent on the Wizards’ season?
Nobody needs Dave’s formula to see that Stephon Marbury, Isiah Thomas, and Mike D’Antoni have produced a combined 0 wins on the basketball court. But the Knicks are on pace to improve over last season.
For that matter, how much did losing Monta Ellis for 30 games *really* hurt the Warriors?
Yeah, it can be tough. But give Win Scores credit for trying.
By the way, this season, Houston has won 25.0% of games where Ron Artest has not played, compared to 69.0% of games with him.
So if we take wins and losses as the only stats that matter, would Artest, McGrady, and Yao be the first, second, and third most important stars to the Rockets’ success, in that order?
Michael
January 1, 2009
Vince, I think the Wizards have declined due to a decline in production from Caron Butler. They also are receiving very little from anyone other than him and Antwan Jamison, without Arenas and Heywood around. So I think if your ‘star’ player declines and you have little production from your role players, the team will find it hard to win as many games as usual!
As far as the Knicks go I have David Lee down as one of the top 15 most productive players in the league this year, and he’s getting a lot more burn (4 more mpg and starting most of them) under D’antoni than in previous seasons. I also see strong play from Nate Robinson, Chris Duhon and Quentin Richardson, and both Quentin and Nate are playing more this year.
With Golden State, although that team seems to be underachieving (at least to me) I don’t think Monta Ellis was ever that important to their success, with their surplus of decent guards and Andris Biedrins being by far their most productive player at center.
For Houston I have Carl Landry and Luis Scola as the main contributors after Yao and TMac, but maybe Ron Ron is already indespensible to team chemistry? All I know is that Houston were a 67% team last year, 63% the year before that, and 63% so far this year. Which does tend to support the notion that Ron does not offer much to this team. I’d also like to note that of those three loses without Artest, one was against New Orleans, one was with T-Mac also injured, and the third was against the Clippers, who were in the middle of a stretch where they won 5 of 7 games including 3 straight with the win at Houston. So I think there are always extenuating circumstances to consider with +/-.
I think currently a strong testament to the WoW method right now is the play of Denver, having replaced AI with Mr Bigshot. Just imagine if they had kept Camby!!
Joe
January 2, 2009
Michael,
No doubt Camby would help. How about looking at the current roster though… their top 2 Est. WP48 players are sitting on the bench quite a bit in Andersen and Balkman.
Joe
January 2, 2009
Balkman actually splits between SF and PF so more like 2 of their top 5.
back2newbelf
January 2, 2009
I don’t really have any evidence that Houston is the 2nd best team in the West but consider this:
– Battier has missed half of their games. Last time they played without Battier(05-06) they finished 34-48. I think Artest allowed them to still be a good team even though a rather important player was/is missing.
Whether Artest can add something to this team when Battier is playing is a different story
-In at least 21 of 33 games, either Alston, Battier, McGrady or Artest were missing. It’s very unlikely all these players will become/stay healthy for the rest of the season but then their mediocre play would have to blamed rather on injuries than Artest
Michael
January 2, 2009
In 2005-06 McGrady missed 35 games and Yao missed 25 games. Leading the team in minutes played for the season was Juwan Howard (not a good thing.) Also Luis Scola and Carl Landry weren’t playing for Houston yet and they are both solid contributors.
I think even if everyone on the roster was healthy, unless TMac reverted to the player he was in Orlando, the Rockets still wouldn’t be serious contenders in the west.
John W. Davis
January 3, 2009
Artest can play for my team!