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.
“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.”
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.
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.
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.
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.
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Our research on the NBA was summarized HERE.
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.