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Tuesday, November 24, 2009

Trevor Ariza's Efficiency Has Plummeted in Houston

Some misinformed "stat gurus" insist that basketball can best be understood without even watching any games, because the eyes are supposedly biased but the numbers are supposedly completely objective. The "stat gurus" declare that a player's productivity is not significantly impacted by his minutes played or by who his teammates are--he is who he is regardless of his environment. For instance, several years ago I (futilely) tried to convince a "stat guru" that Gary Payton did not fit in well with Phil Jackson's Triangle Offense; the "stat guru" insisted that on a per touch basis Payton did exactly the same things in the 2003-04 season as a Laker that he had done throughout his career, even though anyone who has even an ounce of common sense could easily see that Payton neither did the same things nor was he even remotely close to being as effective as he had been earlier in his career. Similarly, Ron Harper struggled initially to fit in with the Triangle Offense when he first signed with Jackson's Chicago Bulls but Harper eventually adjusted to being a role player within the structure of that offense (as opposed to being a 20-plus ppg scorer in other offensive systems previously).

Based on the same kind of erroneous thinking that the above "stat guru" applied to Payton, the Houston Rockets essentially swapped Ron Artest--the 2004 NBA Defensive Player of the Year and a four-time member of the All-Defensive First or Second Team--for Trevor Ariza, a role player who started for the Lakers' 2009 championship team. The Rockets' brain trust believed that Ariza--who clearly benefited from playing alongside Kobe Bryant last season--could emerge as a star in Houston.

Ariza only averaged more than 20 mpg once in his first four seasons. During that time, he displayed little ability to shoot the ball (3FG% of .278 or lower each year, FT% of .695 or lower each year) or to create a shot for himself or others; he served primarily as an athletic, energetic role player who could finish very well at the rim and play solid defense against perimeter players. Then in 2008-09 he played in all 82 games for the first time in his career, logging a career-high 20 regular season starts--including the final 19 games of the season. Ariza also started all 23 playoff games as the Lakers won the NBA Championship. Although his free throw shooting was still subpar at best (.710 FT% in the regular season, .563 FT% in the playoffs), he improved his three point shooting stroke (.319 3FG% in the regular season, .476 3FG% in the playoffs), an upgrade which is directly attributable to Bryant not only because Bryant drew so many defenders that Ariza had wide open looks but also because Bryant provided Ariza with an offseason program specifically geared to making someone a better three point shooter. Presumably, the technical improvements that Ariza made to his shooting stroke should survive being separated from Bryant but Ariza is still a player who struggles to create a shot for himself or others; he is best suited to be a team's fourth or fifth offensive option, not to lead a team in field goal attempts and/or scoring. Consequently, Ariza will be much more efficient in the role that he played last year in L.A. than if he is expected to be the focal point of a team's offense.

Essentially, a "stat guru" looks at Ariza's career year in 2008-09, factors in that Ariza is only 24 years old and projects that Ariza could be an All-Star if he simply played more minutes and got more touches. In contrast, after the de facto Artest-Ariza swap I wrote that in Houston Ariza will most likely remain a solid role player as opposed to developing into a star. I made that conclusion based on analyzing Ariza's skill set, as I described above; I understand that Ariza's 2008-09 productivity is a result of him playing alongside Bryant and that if Ariza's minutes/touches/role are increased he is unlikely to be able to maintain the same efficiency level.

There is still a long way to go in the 2009-10 season but here are the preliminary results of Houston's Ariza experiment: he has started all 14 games for the Rockets, is averaging a career-high 38.6 mpg and is leading the team in scoring (18.3 ppg) and field goal attempts. Do these numbers vindicate the "stat guru" perspective? As Lee Corso loves to say, "Not so fast my friend." Let's look at the whole picture. Ariza is shooting a career-low .388 from the field, though his three point shooting is solid (.343). On a per minute basis, Ariza is averaging a career-low in rebounds and a career-high in turnovers. Ariza's assist numbers are up--on both a per game and per minute basis--but I suspect that this is a result of a small sample size; Ariza had five or more assists in five of Houston's first nine games but he has had four or fewer assists in each of Houston's last five games. Similarly, even though Ariza's overall 3FG% is good the numbers are trending downward at an alarming pace: he made 11 of his first 21 three pointers (.524) but has shot just 23-78 (.294) from long range since then.

The Rockets have increased Ariza's minutes and field goal attempts but instead of "A Star is Born" we are witnessing "A Role Player is Overworked." Ariza averaged 23.3 ppg while shooting .500 from the field (including the aforementioned .524 from three point range) in his first three games as a Rocket but he has averaged 16.9 ppg on .361 field goal shooting (69-191) since that time. Many NBA players are capable of averaging 15-18 ppg if they have the opportunity to fire up enough shots but that does not make them stars. Look for Ariza's field goal percentage, three point field goal percentage and assist numbers to continue to drop as long as the Rockets depend on him to be their primary offensive option--but if stars Tracy McGrady and/or Yao Ming return to action and Ariza is able to resume being a 20 mpg role player then Ariza's scoring average will decline but his shooting percentages will bounce back somewhat.

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posted by David Friedman @ 3:13 PM



At Wednesday, November 25, 2009 12:38:00 PM, Blogger Chubbers said...

Big fan of your writing, but I do have some minor issues with this post.

I agree that some "stat gurus" rely far too much on certain statistics. However, there are many different ways to analyze a player based on stats, ranging from simple +/- numbers to PER. I find it a weak argument to simply group together all "stat gurus" and say that they would proclaim Ariza to be so and so. I would assume that any metric that simply takes into account how many of one's shots were assisted would be far more accurate in this regard.

This is obviously my own opinion but I think there is much value to a good combination of "advanced" statistics and actual observation of the games. The difficult part is just finding the right balance.

At Wednesday, November 25, 2009 1:42:00 PM, Blogger David Friedman said...


Keep in mind that the Houston Rockets rely on "advanced" statistics at least as much as any team in the NBA. You may recall the New York Times story last year about how the Rockets use "advanced" statistics to help Shane Battier defend Kobe Bryant. There is no doubt that such metrics played a major role in Houston's decision to sign Ariza. Beyond that specific point is the general fact that many "stat gurus" do not appreciate how much an individual player's productivity is affected by the system he plays in and the teammates he has. I did not check to see if every single stat metric overvalues Ariza but Houston's signing of Ariza is a good example of the flaws and limitations of relying too heavily on stats to evaluate players.

I agree with you that there is some value in combining "advanced" statistics with observation of games. In general, I think that Houston's GM Daryl Morey does a good job with this--and he may have had non-stat reasons to sign Ariza instead of Artest (Ariza is a younger, lower maintenance player)--but I disagree with the idea that Ariza is some kind of star in the making.

At Wednesday, November 25, 2009 4:05:00 PM, Anonymous Anonymous said...


ariza better than i thought averageing 18ppg per game in houston he also average 4 assist and boards is he a star dont know but a produtive player none the less better than i thought.

i thought he was a role player that just hit open shots when kobe got doubled he is more good passer and rebounder and great defender artest for him is a wash right now he is a better defender than artest at this stage houston 8-6 so he is not padding stats on a bad team he is good.

At Wednesday, November 25, 2009 8:52:00 PM, Anonymous Anonymous said...

Ariza is not paid like an "all-star in the making" so I don't understand why you would criticize his play that way. He was brought in as a replacement for the ever-crazy Artest. It wasn't even the Rocket's idea to "swap" them. Ron pulled a Karl Malone so it cannot be judged as a fair trade scenario even if they are both receiving the same amount of money this year. Artest is the better player but he wanted to leave the Rockets. The Rockets, instead of tanking, looked for a young, athletic, sane replacement.

---The Rockets have increased Ariza's minutes and field goal attempts but instead of "A Star is Born" we are witnessing "A Role Player is Overworked."

The biggest reason they increased his minutes is because they are short-handed. Take out Yao and McGrady's salary and you have a low-budget team performing better than the sum of their parts.

---The Rockets' brain trust believed that Ariza--who clearly benefited from playing alongside Kobe Bryant last season--could emerge as a star in Houston.

It's unfortunate that they lost both Yao and McGrady, but I bet you nobody in the Rockets organization thought that Ariza would be their savior. The Lakers thought he was worth the MLE and the Rockets offered the same amount.

I understand your gripe with stat-gurus, but if you were the Morey, what would you have done? Artest was going to walk regardless, and I admire their decision to use the MLE on a player and not just tank the season. Would you also stop giving Shane Battier data on the guys he guards? What exactly did the Rockets do wrong here???


At Thursday, November 26, 2009 12:56:00 AM, Blogger David Friedman said...


Did you really read the post before commenting?

We'll see what Ariza's assist numbers are by the end of the season; I strongly suspect that this is like an MLB batter who hits .450 in the first month and then finishes with a .250 average. Ariza is not a creator, so I find it difficult to believe that he will maintain this assist average for an entire season (I think that he will finish in the 2.5-3 apg range given roughly the same minutes that he is playing now).

Ariza is not rebounding any better now than he did in the past. In fact, on a per minute basis this is the least productive rebounding season of his career so far. In other words, he is a role player who will give you 4.3 rpg in 24.4 mpg (for the Lakers last year) or an "extra" rebound (i.e., 5.4 rpg) in 14.2 more mpg this season. Essentially, Ariza is playing more than an extra quarter per game for Houston than he did for L.A. and grabbing one more rebound in that added time.

Ariza is scoring more points only because he is taking a lot more shots. His shooting percentage has markedly declined.

Ariza is not a better defender now than Artest, who is bigger, stronger and craftier. Ariza is good at playing the passing lanes and using his length but he struggles a bit against bigger small forwards like LeBron, Pierce and Melo. Obviously, those guys are very hard to guard but Artest is more physically suited for the task and that is why the Lakers jumped at the opportunity to sign him.

At Thursday, November 26, 2009 1:06:00 AM, Blogger David Friedman said...


Actually, Ariza is the one who balked at the Lakers' initial offer to him, because Ariza thinks that he is a star in the making. The Lakers leaped at the chance to sign Artest and thus upgrade themselves at the sf position. No one else believed that Ariza was worth as much as he thought he was worth, so he ended up in Houston. As I wrote at the time, Ariza played himself, going from being a role player on a championship team to being expected to lead a team that likely will not make the playoffs.

I am not criticizing Houston for signing Ariza or even for the contract that they gave him but rather for the stated expectation that Ariza is some kind of star in the making--i.e., the references to the idea that he will have a vastly expanded role. So far, the only expansion in Ariza's role is that he is taking many more shots per game and missing most of them. Ariza is not Scottie Pippen or Joe Johnson--he is not going to emerge as a perennial All-Star. He is a limited player, but he is perfectly suited to be a role player on an excellent team. Instead of possibly making multiple Finals appearances with the Lakers in the next two-three years, Ariza is going to be struggling to get out of the first round with the Rockets.

My criticism is not of the Rockets per se but rather of anyone who seriously believes that Ariza is a star in the making. The main critique that I have for the Rockets in that regard is that I don't think it was wise to fuel fan expectations--or Ariza's expectations, for that matter--that Ariza is going to be a star. Also, considering Ariza's skill set limitations and his sorry shooting percentage, I don't think that he should be leading the team in field goal attempts even with T-Mac and Yao both being sidelined by injuries.

At Monday, November 30, 2009 1:52:00 PM, Blogger Philippe said...

Which quotes from either the Rockets or from Ariza are you using?
Did Ariza actually say he was a "star in the making" or did someone else say that about him?
I followed the signing from the Houston perspective and it wasn't billed or hyped as the signing of a future All-star...
Here are some quotes from an article published in the Houston Chonicle in September:

"I loved playing for the Lakers," Ariza said. "I loved my teammates. I was at home. I could see my family (he has a 17-month-old son, Tajh, in Los Angeles) every day. Sometimes, things don't work out the way they should or the way everybody else thinks they should."
As Ron Artest quickly claimed Ariza's spot with the Lakers, Ariza slid into Artest's with the Rockets. Had the Lakers wanted nothing more than to keep Ariza, he likely would have returned and never wondered what might have been out there for him. But now, with training camp to begin next week and the business of the summer behind him, Ariza has become convinced he needed to move on.
"Every player wants to grow. Every player has goals. Every player wants to be the best player he can be," Ariza said. "In L.A., they have so many great, great players. Kobe is the best player in the NBA, arguably ever. Pau Gasol. Lamar Odom. Andrew Bynum is coming into his own. I think I would have been stuck into one role there. Here, everybody said, ‘We want you to work on your game. You have to do more. We believe you have the skill and the talent to do it. Come do it.'?"

This from Morey on the signing:

"No one wants to limit Trevor. He has potential to be whatever he puts his mind to," Morey said. "We know what he's good at. That's good enough for us. If he is just the Trevor who has been a very good player in the league the past few years, that's what we'll take. But he sets high expectations for himself, and this is a year we're going to need guys to surprise us in a good way.
"Coach (Rick) Adelman and I feel he has that ability. We feel like there are a lot of places we're going to need people to step up. We don't know with which ones that's going to happen. We do feel good about betting on Trevor to be one of the guys."

So, really not sure where you are coming from on this one. There may have been some pundits out there saying Ariza just needed more possesions to become an All-star, but I don't see any evidence of that in this posting...

As always though, your postings stir the pot. Keep'em coming.

At Monday, November 30, 2009 5:21:00 PM, Blogger David Friedman said...


If you search for "Trevor Ariza" and "star" you can find a number of articles suggesting that Ariza either became a star last year with the Lakers and/or will be a star with the Rockets this year. Here are just a few such articles:

Artest to Replace Ariza

The L.A. Times' Bill Plaschke described Ariza as "a 24-year-old kid with a limitless ceiling": Lakers Make Wrong Move Going With Artest

Ironically, the quotes you cited came from an article titled A Star in Waiting?

As indicated in this article, some "stat gurus"--most notably Dave Berri--believe that a team can successfully build around "low usage, high efficiency" players like Ariza. Prior to the season, Berri offered a more optimistic prediction about the Rockets than just about anyone else, based on the belief that Ariza and other role players could play just as efficiently as they did in previous years despite having their minutes and roles increased:

Are You Buying into the Rocket Program?

So far this season, Ariza ranks 10th in the NBA in field goal attempts, which certainly suggests that the Rockets believe (hope) that he can shoulder a star-level load; the players ahead of him on that list are Kobe, Melo, Durant, Nowitzki, Wade, LeBron, Joe Johnson, Bosh and Monta Ellis--and right behind Ariza is another so-called star in the making, Rodney Stuckey.

I am not trying to "stir the pot"; I simply write the truth, whether or not people like to hear it.

At Monday, November 30, 2009 8:51:00 PM, Blogger lakersfoolsgold said...

You should call your site 'keeping them honest'...

that being said i still think the rockets can make the playoffs looking like the 01 sixers; and second, even though there is no question that artest is better than ariza [from someone who watches every lakers game]- his passing alone is way beyond ariza and he actually has a post move and can board consistently [noting that his FT% is horrid]-, though by the end of the contract and perhaps in maybe two years it wouldn't surprise me for ariza to be the better player, at least in terms of where they are in their careers, though ariza will never at his best be as skilled as the young artest

At Monday, November 30, 2009 11:25:00 PM, Blogger David Friedman said...


I assume that your comparison of this year's Rockets to the '01 Sixers is based on the fact that both teams were/are stocked with defensive-minded role players--but the critical difference is that the Sixers had an MVP-level player (Iverson actually won the award that year, though I think that Shaq deserved it) who could create shots for himself and others, precisely the component that this year's Rockets are missing sans T-Mac and Yao. Unless one or both stars return to action, it will be difficult for the Rockets to make the playoffs, though it is not out of the realm of possibility that they could hang on and grab the eighth playoff spot (I placed them just out of the playoff picture in my Western Conference preview).

Your assessment of why Artest is better than Ariza is right on the money and I agree with you that Ariza will never be as good as Artest was in his prime. As for who will be better in two years or five years, clearly Ariza has the edge the further out you draw that comparison because Artest is the older player. Artest is a better fit for the Lakers right now because he can better defend big small forwards like LeBron, Melo and Pierce (in addition to the fact that Artest is better than Ariza in the various areas that you mentioned). Ariza is a very solid role player who can be a nice contributor to a team that already has an All-Star or two on the roster.

At Tuesday, December 01, 2009 7:45:00 PM, Blogger lakersfoolsgold said...

Per my Sixers 01 juxtaposition:

True that they [the Rockets] don't have AI- though I am marginally comparing him to Brooks, who is not nearly as good but capable of getting in the paint as good as any point guard save Paul- or even Mutumbo [01 finger wagging Mutumbo not last year's admonishing grandfather] but Ariza, Scola and Landry are much better than Bell or Geiger or Snow were. And I'll take Hayes over MacCullough.

And I certainly didn't mean to imply the Rockets are getting anywhere close to the finals, recalling how weak the East was then and, by apophasis, maugre George Karl blowing game 7 by not giving Allen the shot [if my memory is correct].

anyway keep up the good work

At Wednesday, December 02, 2009 4:21:00 AM, Blogger David Friedman said...


I kind of understand what you are saying with the Iverson-Brooks comparison but until Brooks makes a few All-NBA Teams and regularly drops 40 in playoff games I just don't think that is a very valid or meaningful comparison. The Rockets do not have a bona fide star player right now and that is their biggest problem--when Ariza (who leads the team in FGA) or Brooks is supposed to be the star, then you in fact have no star.

Although Snow was third on the 01 Sixers in mpg, Bell appeared in just five games (6.0 mpg) and Geiger averaged 15.5 mpg in 35 games, ranking 10th on the team in mpg. The 01 Sixers had an All-NBA Second Team center who won the Defensive Player of the Year Award (Mutombo) snd the Sixth Man of the Year (McKie) paired with league MVP Iverson and three role players who were in their proper roles because of the weight carried by Iverson, Mutombo and McKie (Snow, Hill and Lynch, a key player who got injured midway during the playoff run). Again, it must be noted that until T-Mac and/or Yao returns the Rockets have no stars and are thus forced to put role players into lead roles (Ariza, Brooks, Scola).


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