A: Average Distance Per Shot. It is calculated by taking every shot in a game for a player or team and then dividing the total distance of all shots by the number of shots taken to determine the total ADS. It is meant to be an objective and simple math problem.
Q: Aren't there some complicated issues with ADS that this simple math doesn't account for?
A: Yes. For instance, it doesn't account for defensive intensity. It doesn't account for garbage time. There are a few things it doesn't do. But, if a player shoots 10 shots from a cumulative distance of 190 feet, and another player shoots 10 shots from a cumulative distance of 19 feet, it would seem to give us a larger view of what kind of shots a player gets.
Q: Don't buzzer beater heaves from 84 feet throw off the sample?
A: Absolutely. I couldn't find a way around this, and we actually considered not counting them at all. I didn't like that since sometimes they go in and it also throws off the math of the season. Instead, we have instructed all who collect the data to change any distances of over 30 feet to 30 feet. This will not throw off the totals too much, but still account for one extremely low-percentage prayer.
Q: How do we calculate Dunks and Lay-ups?
A: After careful consideration, we decided dunks should count as a 0-foot FG, and lay-ups should count as a 1-foot FG unless otherwise noted in the PBP.
Q: What is the biggest problem with ADS?
A: Easy, the biggest problem was that shooting fouls do not count as Field Goals Attempted. But, if the idea is to find out which players take the ball to the rim with more consistency, then we must account for a player like Dwight Howard having a dunk but he is fouled hard to keep him from the dunk. So, a solution that we arrived at was to account for every shooting foul that doesn't result in a Field Goal (and 1's do not change) by adding a 1-foot FG to the total. This is called "ADS+"
Q: So, the formula for "ADS+"?
A: Cumulative distance of all shots plus the total number of shooting fouls (1 foot FG per Shooting Foul) earned by total Field Goals + total number of shooting fouls earned.
Q: What is the biggest problem with "ADS+"?
A: No question, the fact that we have no distance data on shooting fouls is disappointing. Until there are advances on the NBA stat sheet that show exactly where the shooting foul occurred, we have no way to distinguish whether the foul was on a 1 footer or an 18-footer. One exception would be if the shooting foul is behind the 3-point line, the player is awarded 3 Free Throws, so we assign that a "23-footer" which is the closest rounded foot for a 3-Pointer.
Q: What are you trying to achieve and learn?
A: Well, you should read the entire essays from last May, Here , Here, and Here . But, basically, here is what I wrote the first time:
My idea is this: Rather than making the claim that the Mavericks "settle" for perimeter shots consistently and claim that the opponent does not, maybe there is a way to actually prove it. I can never measure defensive intensity. I cannot measure desire. I cannot measure the harshness of officiating. BUT, I can measure how far the Mavs and their opponents are from the basket when they shoot the basketball.
The NBA keeps a full play-by-play of every game in which they list the rough estimate of the distance from the basket for every shot attempted in each game. What if I merely tabulated all of the shots and found the average distance for that night's shots? It sounds so simple, and yet it would seem to reveal whether a team was "settling" or "taking it to the hoop".
I feel like this is so basic and yet so telling. It tells us that every team shoots from the perimeter, but some teams shoot much more from the perimeter. It tells us a team like the Spurs - due to penetration and the presence of a post scorer - shoot from very close to the basket quite often. And, of course, it tells us that the Mavs are trying to win a game in which they rely on 20-footers falling in crucial moments. In all of these games, as the game got later (And intensity is turned up) the Mavs had to keep backing up to get shots. Always a bad trend because sometimes those shots fall, sometimes, they get eliminated before May 1st.
Like I said, someone may already keep this stat. Or, maybe it is so simple it has no practical application to NBA minds. But, it would seem to me that if you take 10 footers instead of 20, you have a better chance of making them. Note: Of course, a wide open 20 footer is easier than a contested 10 footer, but over the course of a sample, I believe this evens out quite a bit. Uncontested lay-ups are way easier than uncontested 3's. Contested dunks are easier than contested 3's, and so on.
Q: How is the Data collected and presented?
A: By using ESPN.com and NBA.com's PBP and shot chart data. I have assembled a team of interns who are taking this project on and we are beginning to put together a database that is gathering everything we can as we go. Here are our current charts. We are doing them for each Mavericks game and posting them. We are keeping them for every player in each game and both teams. Here is how a random game (Mavs-Spurs - 12/30/10) looked:
Please offer comments, suggestions, and ideas in the comments below. This is surely a work in progress.