Sunday, July 17, 2016

Betting Market Rankings for the WNBA

The WNB-Ays
I have added the WNBA to my suite of betting market rankings, to go alongside those for the NBA, NFL, MLB, College Football, and College Basketball. The purpose of these rankings is to reverse engineer an implied power ranking from the Vegas point spreads, essentially distilling the combined wisdom of the market.

Here are the rankings as of July 17:

GPF stands for "Generic Points Favored". It is what you would expect a team to be favored by against a league average opponent on a neutral court. By combining the betting over/under with the point spread, I can decompose GPF into its offensive and defensive components, oGPF and dGPF (note: offense and defense are on a points allowed per game basis, rather than points per possession - there is no way to derive implied per possession metrics from the betting data). GOU stands for "Generic Over/Under" and it is what you would expect the betting over/under to be for that team when playing an average opponent.

Saturday, July 16, 2016

Bonus Tim Duncan Chart - Bank Shots

On the occasion of Tim Duncan's retirement earlier this week, I used SportVU motion tracking data to call attention to an unnoticed element of his game: his low and tight, line drive shot arc.

Using that same data, we can also delve into a more well known aspect of Duncan's shooting game: his bank shot. For the bank shots I am able to identify, the chart below shows where Duncan's bank shots hit the glass. For comparison purposes, I also have a chart for all NBA bank shots.
Duncan seemed to favor the upper left portion of the glass, especially compared to the league average, which is clustered far more in the center, just at the top of the backboard's inner square.

On an unrelated note, I noticed that there appears to be a bias to when a scorekeeper will classify a shot as a bank shot, and that bias is skewed towards made shots. I have found several examples where the motion tracking data clearly shows a missed bank shot, but the official shot description does not call it out. For that reason, I would be skeptical of any stat that shows a particular player is far more effective when shooting bank shots.

Once I have the methodology cleaned up, I hope to use the SportVU create a deeper dive into the bank shot and the underlying physics (similar to last summer's post on the effects of air drag on a basketball's trajectory).

Monday, July 11, 2016

The weirdest thing about Tim Duncan

Tim Duncan announced his retirement today, after 19 seasons in the NBA. On Duncan and his impact to the game, there is no shortage of articles, retrospectives, and in-depth analyses (statistical and otherwise) from which to choose today, most pre-written, no doubt.

Duncan was famous, paradoxically, for not attracting attention to himself, and his retirement announcement was no exception. Contrast Duncan's brief, matter of fact press release (not even a press conference) to Kobe's season long, air ball ridden farewell tour. I wonder how far off the Onion's version of Tim Duncan is from the real thing: Tim Duncan Raving About Health Benefits of Standing Bench, Tim Duncan Around if any Spurs Have Questions About Sequester, Tim Duncan Sends Teammates Google+ Invitations for Fifth Straight Day (I will miss the Onion's Tim Duncan almost as much as Uncle Joe Biden).

But behind Tim Duncan's staid, middle of the road public persona lies a hidden deviancy: his shooting arc.

Using location data tracked by the NBA's SportVU camera system, we can analyze player shooting mechanics in exhaustive detail. For more background, see my introductory post on this topic from last year, as well as some more recent research on free throw shooting.