The summer is a great time to look at your past seasons statistics as an evaluation tool. Therefore, the newest edition of our coaches corner summer series is focused on basketball statistical analysis.
In our most recent blog, Coaches Summer Reading List, we referenced fifty books that could be of interest to coaches. One of those books was “Basketball on Paper” by Dean Oliver. He has an excellent chapter in which he does a statistical analysis of what he calls the “Four Factors of Basketball Success”. Below is his list and what he computes as the relative percentage of importance of each factor. He recommends that coaches chart these for their own team, as well as their opponents, creating eight factors, and use the results for analysis. The first post of the series discusses the use of Effective Field Goal Percentage to evaluate your team and players’ shooting. Enjoy!
Four Factors of Basketball Success
- Shooting (40%)-Effective field goal %
- Turnovers (25%)-Turnover %
- Rebounding (20%)-Offensive rebounding %
- Free Throws (15%)-Free throw rate
We will focus on each each of his factors in separate posts during this mini-series in order to allow the proper amount of time for each. In keeping with his rating, the first factor discusses the use of Effective Field Goal Percentage to evaluate your team and player shooting. Enjoy!
Effective Field Goal Percentage-eFG% – The Most Important Factor of Basketball Success
eFG% is the measurement of your team or player success from the field. It is calculated by assigning a worth of 1.5 for made three-point shots. While this may seem obvious, field goal percentages are not calculated this way but are instead calculated separately for 3-point and total attempts. Looking at field goal % this way allows you to account for 3pt% and 2pt % with one statistic. The formula for calculating the eFG% is (2pt FGM + 1.5 * 3pt FGM) / FGA.
This site provides a simple eFG% calculator to help you so that you will not have to subtract the 3pt FGM from the total FGM since the calculator does that for you.
There are many ways to use eFG%. Here are a couple of thoughts. As with all stats it is important to look at what you are trying to do both offensively and defensively. A hypothetical team had a 53.27% eFG% while their opponents had an eFG% of 46.34%. The second figure would be your eFG% defense. The gap between the two is almost 7%, very good for any team. Any positive gap is good and the greater the positive margin between your team and your opponents the better. Coaches can look at ways to improve both their teams offensive and defensive efficiency, both on 2-point and 3-point field goal attempts, especially if the gap is a small positive one or negative. Coaches can also look at changes from season to season to analyze reasons for those changes. For comparison purposes, college teams generally have an offensive eFG% range of 60%-40%, and players generally have a range of 75%-40%.
Another way to use the eFG% is to look at individual players and their effectiveness offensively. This is the easiest of the four stats to do that with. Let us take for example a young player who is inconsistent offensively but was a highly effective rebounder and defender and played many minutes as a starter. The player had an eFG% of 50.20%, rather good for a young player. When you separate out the 2-point FG% (51.9%) and 3-point FG% (28.6%), it is tempting to coach the player to eliminate 3-point shots. However, any improvement this player makes from 3-point range will have a greater effect than improvement from 2-point range, and it would be easier to do if the player were already highly effective from 2-point range. Another way to use eFG% is to look at your entire team’s individual eFG%. If one player is at the top and is a good defensive player, wouldn’t it make sense to have that player in the game as much as possible? Just a couple of thoughts about using eFG%, and you can probably think of many more.
Stay tuned for the next blog, Turnover %!