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March 27, 2008

Where Players Take and Make Shots

Posted by Eli in Raw Stats

I haven’t posted in a while, but I have a good excuse. I’ve been assembling a database of play-by-plays from the last five seasons. This will make it much easier to investigate many areas of the game. It’s not completely finished yet, but already there’s a lot of interesting stuff that I can pull from the database. For example, I can quickly calculate that in the four seasons from 2003-04 to 2006-07 (I’m missing a few games, but I have over 99% of games from that time period), there were 14,216 hook shots taken. 45.5% of those shots were made, 54% of those makes were assisted, and 4% of all hook shots were blocked. But that’s not what I really want to examine in this post. Instead I’m going to look at shot location data.

During all NBA games, diligent game charters sit courtside and mark the location of every shot taken on the court down to the square foot. I believe this is done by using a stylus on a touchscreen monitor with a replica of the court on it. This is the source of the shot charts you can see after a game on ESPN.com or CBS Sportsline, and of the compiled shot charts of NBA.com’s Hot Spots (which I discussed in my first post). With the play-by-play database I’ve constructed it’s possible to look at this shot location data in a number of ways.

First, below is a picture showing where players shoot from. Again it’s based on data from 03-04 to 06-07. The court dimensions are to scale, and each one-foot by one-foot square on the court is color-coded based on the number of field goal attempts from that spot. The color scale runs from blue (few FGA) to yellow (some FGA) to red (many FGA). Obviously the charted locations aren’t 100% accurate, but there are still some very interesting patterns that emerge.

Where Players Take Shots - FGA by Location:

Next, below is a picture showing how well players shoot from different locations. The color-coding is based on the field goal percentage from each spot. Because some one-foot by one-foot squares had a very low number of shot attempts, I grouped the data into three-foot by three-foot squares to reduce the noise (so the shading for a single 1×1 ft square actually represents the FG% in the 3×3 ft square that it’s in the center of). Again, the color scale runs from blue (low FG%) to yellow (average FG%) to red (high FG%).

Where Players Make Shots - FG% by Location:

Finally, this last picture looks at what percent of the made shots from various locations were assisted. For this one I used the basic one-foot by one-foot squares, with the color indicating the percent of the made shots from that spot that were assisted. The color scale is the same - blue (low percentage of makes assisted) to yellow (medium percentage makes assisted) to red (high percentage of makes assisted).

Which Shots are Assisted - Assists/FGM by Location:

Obviously a lot could be said about all of these pictures, but I’ll leave it at that for now. I mainly just wanted to give a preview of some of the kinds of things I’ll be looking at in future posts using data from this new play-by-play database.

UPDATE: I’ve added a few more charts in a new post.

12 Comments »

  1. Wow, neat stuff, Eli. Thanks for posting this!

    It certainly seems like an overlay based on the first two could be instructive in helping coaches find the optimal locations on the floor to focus their offense (and their defense).

    The last indicates to me that assists disproportionately are awarded for three point shots, which are often assisted via a relatively simple pass. Shots ‘created’ in the lane seem to be more likely to be made, but less likely to be assisted.

    Comment by Westy — March 27, 2008

  2. How come there’s such a high FG% for shots taken along the baseline (picture 2), in areas where shots are only taken rarely (picture 1)? According to that I’d have my team take more shots from behind the basket. What am I missing? Nice work, btw.

    Comment by Pete — March 27, 2008

  3. I guess it’s not in your data, but I’d love to see the difference zone defense makes here, compared to man-to-man. Maybe a comparison to Euroleague data could be useful here.

    Comment by Pete — March 27, 2008

  4. One thing I’d be interested to see is the efg from each spot. From the chart, it looks like shooting percentage goes down at the 3pt line, which is not very surprising. However, the 3 is worth that extra point. Great stuff, though.

    Comment by kjbMarch 27, 2008

  5. I agree with kjb, I’d like to see the chart with expected points as well

    Comment by kh — March 27, 2008

  6. I like all those assisted buzzer-beaters.

    Comment by silvtown — March 27, 2008

  7. Pete, I’m not sure what’s going on with those baseline shots. I’ll have to look at the data more closely.

    Kevin, I just posted an eFG% chart (and a blocks/FGA chart) in a new post.

    Comment by EliMarch 27, 2008

  8. Hey guys, not too sure the 3rd graph is all that useful.

    It’s fairly common knowledge that 3-point buckets are usually assisted (extremely difficult to “create” a 3 point shot off the dribble). Hence, it makes sense that would appear in red.

    However, (and there is a modest different between professional and college play) the majority of assisted shots come in the form of layups or short-range shots. Obviously, this is also where the majority of all shot attempts take place.

    The 3rd graph unfortunately can lead to incorrect conclusions, such as the one drawn by Henry Abbot of TrueHoop - “One thing that really stands out to me looking at these: if you want to get big assist numbers, play with good three-point shooters. That’s where the assists are.”

    I would venture to counter, “if you want to get big assist numbers, play with good finishers (e.g. the “big” in a pick-and-roll offense). That’s where the assists are.”

    Again, the 3-point shot is difficult to make unassisted, but also the majority of assits are difficult without layups/dunks.

    Comment by Calvin Y. — March 27, 2008

  9. That why people should stop talking about Lebron being a great passer. I hate to sound like I’m bashing the guy, but his passing does not impress me at all since most of his assists are to 3 pt shooters. If you want to impress me with Lebron, note the fact that he can get to the basket and finish any time he wants, that gives me nightmares.
    It’d be interesting to see how many possible assists turn into fouls. I’m a Laker fan and I get frustrated sometimes when Kobe makes a sweet pass to Ronny and then he gets fouled and doesn’t finish (understandably).

    Comment by Marty — March 28, 2008

  10. Dear Sir,

    I am the coach of the Dutch National under16 team men. I am interested if you also has a chart where the misses would have dropped on the floor in relation to the spot where the shot is taken?
    Im other words where are the most likely spots for the rebound? Is that the 70% offside or is it something else.

    With kind regards,

    Bert Samson

    Comment by Bert Samson — April 3, 2008

  11. Unfortunately I do not have data on the location of players when they grab rebounds, so I can’t construct a chart for that. You should check out this article though, which used video tracking to look at where rebounds end up on the court:

    http://82games.com/rebounds.htm

    Comment by EliApril 3, 2008

  12. Eli:

    Any way I can get some of you play-by-play data for the earlier seasons?…I have an NBA database going back to 1991-92, but am looking to get NBA play-by-plya data back to 2003-04 (or maybe even 2002-03) from anyone who has personal databases…I already have most of 05-06 and ALL of 06-07 to the present…

    Any help would be appreciated or if you can point me someone who does have it, that would be great and my email is 7brewers@gmail.com…Thanx…

    Steve

    Comment by Steve — January 13, 2011

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