Measuring How the Hornets Create and Finish Shots

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Published: January 25, 2010

Basketball is a deceptively simple game.  On offense, five guys work together to generate a good shot for a player who can knock it down.  On defense, five guys work together to try and make the opposing team take bad shots, and miss them.  Simple, right?

The concept may be simple, but for a long time, there have been few publically available statistical stats that could help people like me more easily understand the details behind those simple ideas.  Sure, I had FG%, and eFG%, and TS%, but other than three-pointers I  didn’t really have any readily available statistical information to evaluate the types of shots the team was getting – or their success with those types of shots.  Were they at the rim?  Were they 20 footers?  No clue, unless I charted the game myself.

Happily, that has changed over the past couple years, as play-by-plays and the resulting available stats have progressed to the point that we now know the types of shots teams and players are taking, how successful they are from specific places on the floor, and how they compare to the other teams in the league.  My personal favorite site is now Hoopdata.com,(in fact, when I was first directed there, I had a bit of a statgasm) which has a wonderful set of sortable data.   I have probably spent hours pouring over their numbers now, and I wanted to talk about one derived stat that stood out to me:  XeFG%.

XeFG% is the Expected effective Field Goal percentage for a team.  It takes the types of shots they get – I.E. number of shots taken at the rim, from closer than 10 feet, from 10-15 feet, from 16-23 feet, and from downtown – and then takes the league average for shots of those types, and derives what the team should be expected to produce on those shots. Now, before your eyes glaze over, these numbers are useful.  They give us two bits of information:

  • How good the team’s offense is at generating high percentage shots
  • How good the team is at converting the shots they get.

The same sort of information is available for opponent percentages per team, so you can judge just how good your team is on the other end of the floor too.  To illustrate, we’ll start with the Hornets. (of course)  Then I’ll go on to some other interesting teams like Charlotte, Portland, and OKC.

Offense

The Hornets take 30.5% of their shots at the rim, 10.1% from inside 10 feet, 10.2% from 10-15 feet, 24.3% from 16-23 feet, and 24.8% from deep.  For a perfectly average NBA team, that shot distribution would generate an effective field goal percentage of 49.6%.  Given that, we can address the two items listed above:

How good are the Hornets at generating high percentage shots? 

The answer is average.  An average NBA team generates shots that have an expected effective field goal percentage of 49.68%.  The shots the Hornets get over the course of a game have an expected field goal percentage of 49.6%.  So as far as the Hornets go, their execution isn’t anything special.  Still, the question remains – West is better than average mid-range shooter.  The Hornets have some good three-point specialists.  Maybe those shots may not be the best for the league as a whole, but for the Hornets, they could be great. So . . .

How good are the Hornets at converting the shots they get?

Sadly, average again.  The Hornets hit the shots they generate at pretty much an average rate.  They convert them at 49.65%.  They are expected to convert them at 49.6%.

Defense

Opponents of the Hornets take 33.1% of their shots at the rim, 8.9% from inside 10 feet, 9.7% from 10-15 feet, 25.4% from 16-23 feet, and 22.9% from deep.  For a perfectly average NBA team, that shot distribution would generate an effective field goal percentage of 49.8%.  Given that, we can address the two items listed above:

How good are the Hornets at stopping high percentage shots? 

Slightly below average.  Like I said above, an average NBA team generates shots that have an expecteed effective field goal percentage of 49.68.  The shots the Hornets allow over the course of a game have an expected field goal percentage of 49.8%.  So they give up slightly more high-percentage shots than other teams.  So, the next step is – do the Hornets contest the shots that are given to make them bad shots?

How good are the Hornets at contesting the shots they give up?

Sadly, well below average.  Hornets opponents hit the shots they generate at a 7th best rate(for them) of 51.04%.  Those teams were supposed to hit them at a rate of 49.8%.  So the Hornets give up slightly better shots than most teams, and then contest them badly.  Not a great combination.

The Rest of the League

There are a few other teams I thought I’d mention due to their somewhat abnormal results.  So far the Bobcats have fulfilled the pre-season expectation that they’d be one of the worst offensive teams in the league and would rely on a tough defense to carry them through games.  Freakishly enough, however, the Bobcats are actually the best team in the league at generating high-percentage shots.(41% of their shots at the rim!)  An average NBA team taking their shots would be expected to produce a league-leading eFG% of 51.4%.  Sadly, the ‘Cats only convert those shots at a 48.5% clip.  Of all the teams in the league, only Houston produces a similar discrepency between quality shots and actual production.

On the other end of the spectrum is Portland.  The Trailblazers are fifth from the bottom of the league at generating high-percentage shots, yet they still manage strong shooting percentages from the mid-range, which allows them to post the 9th best eFG%.  Weirdos.

Defensively there aren’t as many outliers.  I have a feeling that’s because teams that are disciplined enough to only give up bad shots typically are disciplined to properly contest them too.  There is one team, however, that has some very strange results:  Oklahoma City.  The shots opponents get against the Thunder would typically result in a 4th best(for the opponent) effective Field Goal Percentage of 50.3%.  Instead, and I think this has to do with the freakishly long limbs of Durant, Westbrook and Sefolosha, the Thunder contest well, and only allow a 2nd-best “opponent eFG%” of 47.11%.

There are a few other outliers as well, so if this sort of things interests you, I strongly suggest you go spend some quality time at Hoopdata.com.  The place rules.

Enjoy the game tonight – another tough one on the road against the injury-depleted, but very deep Portland Trailblazers. 

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