How eFG Percentage Can Trick You

Stats can be misleading. In fact, you might see a trend from a statistic based on a strategic adjustment you made. And you view the trend as a positive thing, so you stick with your strategic change.

However, you are actually losing more games because of this change. It's impacting other aspects of the game as well.

From a simplistic perspective, your offense can affect your defense, and your defense can affect your offense.

Let's take a look at an effective field goal percentage and see how this might happen.

Effective Field Goal Percentage, or eFG%, is calculated the following way:
(2pt FGM + 1.5*3pt FGM) / FGA

This means a made three-pointer is worth one and a half times as much as a made two-pointer.

A player who shoots 4 for 10 on all two-point baskets has a standard FG% of 40% and an eFG% of 40%.

But, if all those makes were three-pointers, that player's eFG% is 60%, reflecting the extra value of a made three.


Shoot A Lower Percentage And Score More Points!

Coaches really like this eFG% because you can shoot a lower percentage, but score more points.

Let's take a look at an example and how this can possibly deceive you.

When you played the same opponent during the season, you noticed this occurred. Note, we're going to exclude free throws for the point totals.

Game 1 - You shot 52% and scored 53 points.

You made 26 of 50 shots. You made 25 two-point shots and one three-point shot.

Game 2 - You shot 44% and scored 58 points.

You made 22 of 50 shots. You made eight two-point shots and 14 three-point shots.

Well, the eFG% was higher in game 2!

The knee-jerk reaction is that you need to shoot a higher volume of 3-point shots, like in game 2. Even when you missed more shots in game 2, you still scored more points.


Game 1 Game 2
Made Shots 26 22
Missed Shots 24 28
FG% 52% 44%
Made 3-Point Shots 1 14
eFG% 53% 58%
Total Points 53 58


HOWEVER... There Is More To The story. You Still Lost Game 2!

As you evaluate the two games even more, you realize there were some other consequences that affected the game.

Game 1 - The opponents only scored 48 points, and you won the game.

Game 2 - The opponents scored 60 points, and you lost the game, even though you had a higher eFG%!

Simple, right? You just played bad defense.

However, when you watch game film. You noticed that your half court defense looked better in the loss (game 2) than in your win (game 1).

Then you noticed something else. Your opponent was getting a lot of fast break opportunities.

In fact, your opponent had 10 additional fast break points in game 2.

Then as you analyze things further, you noticed 80% of their fast break points came off of 3-point shots due to the long rebounds.

So not only were you giving the offense more fast opportunities, you were giving them better fast break opportunities.


Game 1 Game 2
Made Shots 26 22
Missed Shots 24 28
FG% 52% 44%
Made 3-Point Shots 1 14
eFG% 53% 58%
Total Points 53 58
Opponent's Points 48 60
Opponent's Fast Break Points 5 15
Opponent's Fast Break Points - Off 3 Pt Shots 2 12
Outcome Win Loss


Your Opponent's Best Player Played Way Better In Game 2

You also notice that their best player was a much bigger factor in game 2.

The player scored 24 points and scored their last 6 points in the final minute to beat your team.

Where in your victory (game 1), they only scored 8 points. They only played 16 minutes due to foul trouble. They were also more tentative and out of sync because of this.

Well, why did this happen?

In game 1, you were a lot more aggressive attacking the basket and even feeding the post. You took fewer 3-point shots.


Stop Taking 3 Point Shots?! Nope...

Now, this example isn't meant to discredit taking three-point shots and looking at the effective field goal percentage.

However, you need to look at the big picture. You can't look at one offensive stat and assume there aren't other consequences.

In this article's example, you might find that tweaking when and where your 3-point shots are attempted improves your results.

Maybe you want to take more 3-point shots early in the possession before the defense gets back.

1 - This could help because more of your slower players are further from the basket and in a good position to transition back on defense.

2 - Additionally, maybe you don't have a super athletic team. But you have one or two athletes that are great at getting up and down the floor. This allows them to crash the offensive boards and get more rebounds because they are going against fewer defenders.

Perhaps, you want more 3-point shots from the corner because the misses don't bounce as far towards half court. Thus, giving your defense more time to get back and reducing high-percentage fast break opportunities for the opponent.

Additionally, evaluate your individual situation. Just because something works for the Golden State Warriors, Duke Blue Devils, or UCONN Huskies doesn't mean it will work for you.

It doesn't matter how your past teams have performed doing X. It doesn't matter what college stats, NBA stats, or stats from any other level might tell you.

These stats can help guide you, but you need to figure out what works for the team that you are coaching.

Resource: Breakthrough Basketball Stat Tracking App For Coaches and Parents



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Tad says:
11/1/2017 at 8:23:29 AM

I agree, somewhat... Stats can definitely be deceiving. You need balance, meaning you must do both. 3 point shots are critical but you should insist that the majority of the ones you take are uncontested. Good ball movement and moving without the ball gets you a lot of those. Also, your players ability to attack the paint will cause most defenses to collapse to protect the rim. When they do there will be open shooters on the perimeter. If not, then plenty of 1v1 shots at the rim. Good spacing and effectively attacking gaps creates those opportunities. An additional benefit to attacking the rim is getting to the FT line.

So I teach, offensively to:
Attack gaps and closeouts (2pts & FTs)
Make the extra pass for uncontested shots (3pts)

Important factor, if your team can't make a good pass, catch a pass, dribble, make a layup, FT or jump shot, then none of this really matters.

You might ask, where does this leave the midrange shot? Effectively dead. Some (many?) will disagree but there's a reason it's a dying 'art form'. Statistics support abandoning those shots, or at least minimizing them to attempt only when they're uncontested. The problem is that too many of them ARE contested and thereby less effective.

Because 3pt shots are so important to the game I'm not sure how to address this with really young players. Except that perhaps you limit them to the kids who are comfortable taking them. But my general feelings on limiting youth players is it's a bad idea to do that. I think I'd rather teach them what a good, uncontested 3pt attempt looks and feels like.

Just an opinion of a coach who has coached a collection of 5th grade girls to current 11th graders. Most are now Division 1 prospects who can handle the game at an advanced level. But I've evolved over the years to realize that simplicity is best and that teaching them HOW to play is more important than running plays (and yes, we run actions...). When I restart with 4th & 5th graders in a year or so I'm confident this will continue to be my perspective.

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Maxwell says:
11/1/2017 at 9:03:30 AM

What a straw man argument!!

So your saying because you shoot threes your team won't be as aggressive and will play worse defense? That makes little sense to me and sounds like a coaching issue. The object of the game is to score points while making the other team not score points. If you can score points by shooting fewer shots why wouldn't you do that? You made 4 less shots and scored 5 more points.. If you can't stop their last best player in the last minute or get back properly on defense after a missed shot, then that is an issue of emphasis, not of shooting to many 3s.

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Joe Haefner says:
11/1/2017 at 3:06:23 PM

This is not an argument of whether you should decrease or increase the number of your 3-point shot attempts.

It was imply meant to imply that you need to analyze your situation and not draw conclusions by simply looking at a stat.

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Michael Broussard says:
11/1/2017 at 10:51:39 AM

Only for iTunes iOS well that leaves me out.
This was exactly the type of app I have been looking for.
I''m waiting.....

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Stan says:
11/1/2017 at 4:02:45 PM

This is the problem with all static analysis (e.g. Four Factors) -- not all possessions start the same way (offensive or defensive). A dynamic analysis accounts for this. If you get 4 steals leading to easy layups, your shooting percentage is better but not because of improved offensive execution. This is one big reason that getting to the free throw line helps you win. It helps your defense!

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