Category Archives: Research Papers

To tank or not to tank

Last week, I mentioned that my paper with my PhD cohort Chris was accepted for the poster session at the MIT Sloan Sports Analytics Conference. I’ll give the summary and some pictures today (you can find the full paper on my academic website). The project looks at the age old subject of tanking for position in the NBA draft lottery. We answer two questions:

  1. Should teams tank for a better draft position?
  2. How much do teams actually tank?

For the first question, we head right to the lottery. We are interested in the causal effect of obtaining the top pick in the draft. If the first pick is truly valuable, then teams should be willing to lose intentionally to get it. LeBron James, Tim Duncan, and Shaquille O’Neal were all first picks, but so were Greg Oden and Michael Olowokandi. We want the average value of all the first picks since the draft lottery took its current form in 1990.

Since there is some randomness in who wins the lottery, Continue reading

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Since the dawn of Linsanity

Since it all began for Jeremy Lin on Saturday, February 4th against the Nets, Jeremy Lin has shot 42-73 from the field (58%!) over four games. Lin’s shooting percentage his senior year at Harvard? 52%. His first four games as the starter for the Knicks are even more anomalous considering that he is only 3-14 from three point range. He shot 60% on two pointers his senior year, compared with 66% over the last four games.

You probably know what’s coming. That’s right, Lin has had a great start to his career, but also a lucky start. Although his performance has transformed the Knicks’ demeanor, don’t expect the insane shooting to continue. Teams will also start backing off on pick and rolls to see if he can reliably make NBA threes. If you still want to jump on the bandwagon, Brother Conor can tell you what to expect.

I also have great news today! One of my submissions to the Sloan Sports Analytics Conference was accepted for the poster session. The paper (available at my academic website, written with Christopher Walters) estimates the causal impact of NBA draft incentives on tanking as well as the causal impact of winning the NBA draft lottery. In short, we find that teams tank a lot — teams that can improve their draft position by losing have lower winning percentages than teams that can’t by about 15 percentage points. There’s good reason for all this tanking. After adjusting for team quality, winning the draft lottery provides a four year attendance boost (though only a small increase in winning percentage). I’ll explain the details in a future post.

Maximizing offensive efficiency

During Kobe’s “hot streak,” I’ve been writing that he’s actually inefficient compared to Andrau Gasnum, the Lakers’ superb tw0-man post presence. I’ve said that he should give up some shots until his efficiency equalizes with Gasnum’s. Adrian the Canadian was quick to send me a Sloan Sports Analytics Conference paper arguing that teams  might equalize offensive efficiency too much already. The author (Brian Skinner) uses some network theory for unknown reasons (it’s not related to his point), but the paper boils down to Continue reading

Sucking wind in La Paz – Sloan Sports Analytics Conference poster

Last year, I ran across an article analyzing whether high altitudes matter in South American international soccer. The authors run regressions with the away team’s altitude change as an explanatory variable and find that climbing but especially descending hurts the away team. Descending 2,000 meters seems to lower away team winning percentage by over 10 points. Pretty surprising finding.

However, these regressions only control for home team quality. It just so happens that Bolivia, Ecuador, and Colombia (i.e., the descending teams) are historically weak teams. What we have here is omitted variables bias — the naive analysis implies that descending harms performance, when in reality descending teams just aren’t very good.

On my quest for causation, Continue reading