Is Trevor Ariza Really the Key to Fixing Houston Rockets Defense?
The Houston Rockets' biggest acquisition this offseason, Trevor Ariza, has been touted as the solution to their defensive problems. How true is that supposition? Ariza is a good defender, but is he enough to vault them into the top 10?
There are reasons to think that he can be, but without resolving some other issues, there’s no assurance that he will be the solution to the Rockets’ woes. We’ll look at where he can help, where he might help and where he can’t help.
How Ariza Can Help: The Power of Three
First, let’s establish that while Houston did not have a top-10 defense, it didn't have a woefully awful one. It had a defensive rating of 106.3 last year, which was good for 13th in the NBA, per Basketball-Reference.com.
When looking at the best defenses, you can see a trend: They almost all have three plus defenders and one elite defender.
There is no perfect defensive stat, but one of the better ones is “defensive real plus-minus” or DRPM. According to Steve Ilardi of ESPN.com:
"Drawing on advanced statistical modeling techniques (and the analytical wizardry of RPM developer Jeremias Engelmann, formerly of the Phoenix Suns), the metric isolates the unique plus-minus impact of each NBA player by adjusting for the effects of each teammate and opposing player.
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Last season there were 437 players who hit the NBA court. Of those, 163 played at least 30 games, averaging 25 minutes. And out of that subset, just 54 maintained a DRPM over 1.0.
That means about one in eight defenders were able to maintain those high standards. We’ll set that as a standard for a plus defender.
There were just 19 players (4.3 percent), who had a DRPM of 3.0 or higher. We’ll set that as the standard for elite.
There are just seven teams who had three plus defenders with at least one of those being elite. Here they are, along with the combined DRPM of the players who qualified, the team’s defensive rating and where that ranked in the league:
| Team | Players | DRPM | DRTG | DRTGRK |
| IND | 3 | 8.17 | 99.3 | 1 |
| CHI | 4 | 10.7 | 100.5 | 2 |
| SAS | 3 | 8.85 | 102.4 | 3 |
| GSW | 3 | 11.25 | 102.6 | 4 |
| WSH | 3 | 9.16 | 104.6 | 7(T) |
| MEM | 3 | 9 | 104.6 | 7(T) |
| LAC | 3 | 7.32 | 104.8 | 9 |
The seven teams who met that qualification were among the top nine defensive squads in the NBA. Clearly, having three plus defenders and one elite defender goes a long way toward making a team a top-five defense.
If you’re a fan of the Rockets, that should be encouraging news, as Houston already has Dwight Howard (4.91) as an elite defender and Patrick Beverley (1.29) as a plus defender. Ariza (1.04) puts the Rockets in that three-and-one category.
Three plus defenders can cover the failings of two much easier than two can help three. It’s what I call the tipping point, and it’s apparent that it does come into play.
How Ariza Can Help: Elite Ball-Stopper
All of that said, the man Ariza is replacing, Chandler Parsons, wasn't a bad defender in his own right. His DRPM was a respectable 0.59.
However, there is a larger distinction when viewing how they guard elite players.
Using the player comparisons at NBA.com/STATS, I compared what the top five small forward scorers did while Parsons and Ariza were on the court. Here they are, per 48 minutes, along with their season averages:
The chart shows that while the elite scorers tended to do better than average against Parsons, Ariza consistently held them in check. Having that first-tier stopper is a huge asset, and Ariza is clearly on a different level than Parsons when it comes to holding down the best.
How Ariza Might Help: Keeping James Harden Interested
A huge question mark for Ariza and the Rockets remains: Can he keep James Harden interested in playing defense?
Let’s be fair about Harden without being overly forgiving of his obvious flaws. He is responsible for carrying the team on offense, so it’s too much to demand that he carry the defense too. And, when he is paying attention, he’s a decent defender.
Having said that, when he’s not engaged, Harden is an utter liability defensively, and he’s not being asked to carry them on that end; he’s just being asked to stay focused.
His recent FIBA performance illustrates his inconsistency perfectly. He was third in the tournament in steals per game with 2.1, indicating that he sometimes does play good defense.
Then, as Mike Prada of SBN pointed out on Twitter, there were also times when things like this happened:
There is carrying a defense and there is being completely oblivious to where your man is, with considerable room between those two extremes. For the Rockets to become an elite defense, Harden only needs to be aware, not great.
Ariza has a championship ring. He’s a respected, veteran leader. He has the grounds to communicate with Harden on the court, keep him engaged and help him stay cognizant of his responsibilities.
That said, if Harden is apathetic, Ariza can’t help. Only Harden can make Harden want to stay engaged during the full shot clock.
Truthfully, the Rockets are better served with Harden improving his help defense over expending his energy on the ball. His long arms would be great for closing off passing lanes, and with his strength he’s a good candidate for helping with a switch when necessary.
If he can just provide reliable help defense, he can find that middle ground between being a liability and carrying the Rockets on both ends of the court. Ariza makes that possible by being the elite wing defender teams need.
How Ariza Can’t Help
The Rockets lost Omer Asik. He wasn’t critical to them, but he was important. One of the best things Houston had going for it last season was it could rest Howard and lose almost nothing defensively. Asik's DRPM of 4.87 was nearly identical to Howard’s.
As a result, Houston gave up just the 10th-fewest points to opposing benches according to HoopsStats.com.
ESPN.com lists Donatas Motiejunas—whose DRPM was 0.53—as the new backup 5. He is not on the level of Asik, and the Rockets are going to have more problems stopping opponents when they rest their starters as a result.
Ariza can’t help with with that. In fact, it’s possible the gains that come from signing him will be somewhat offset by the loss of Asik on the bench.
That disclaimer comes with a caveat, though: The loss of Asik won’t matter when the game is on the line. Having three good-to-great defenders on the court in must-stop situations is how a team can turn two or three losses into wins. Houston now has that potential.
Ariza is a definite help to the Rockets' defense, and if he can get Harden to commit to team defense, his value will be even greater.
However, the problem with the lack of bench defense is still unresolved, and without that solution the Rockets may have taken two steps forward and one step back. Still, finding a player who can help there is a much smaller dilemma than acquiring an elite wing stopper. And considering the Rockets didn't have that far to go anyway, they should be a top-10 defense.
Ariza might not solve all the problems on defense, but he is the answer to most of them.
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