Effective Field Goal Percentage (eFG%) 9/14/2009

Most boxscores only contain the standard FG%, but that statistic is outdated and doesn’t provide a true picture of a players shooting accuracy.  I prefer to use the more descriptive ‘Effective Field Goal Percentage’ (eFG%).

Effective field goal percentage is determined by the following formula: 

eFG% = (FGM + (.5 x 3PM))  / FGA

The eFG% statistic takes into account how far away from the basket a players shots actually came from.  Three pointers are given more credit than two pointers.  For example, if you are trying to compare the shooting ability of two players, say Chauncey Billups and Derrick Rose, eFG% can be really helpful.  Last season Billups had a FG% of 41.8% while Rose put up a FG% of 47.5%.  Seems like a very clear answer, Rose is a better shooter.  But you would be incorrect.  Plugging in the numbers you get a completely different answer.

Billups:  410 FGM + (.5 x 162 3PM) / 980 FGA = 50.1 eFG%

Rose:  574 FGM + (.5 x 8 3PM) / 1208 FGA = 48.2 eFG%

Now it becomes clear that Billups is actually the better shooter of the two players.  Billups puts up a lot of shots at a much greater distance away from the basket than Rose does, which requires better shooting skills.

Now, the real trick is applying this information to make fantasy decisions.  For example on one night we have a situation where Rose and Billups are both playing teams with very strong interior defense.  Which PG  would you want based on FG%?  How about on eFG%?  Facing a tough interior defense, you definitely want the better outside shooter, which is Billups.  You wouldn’t know this if you only used the simple FG%, but the roster decision becomes easy if you use eFG%.

Many people also use True Shooting Percentage (TS%), but I really don’t like that statistic.  True shooting percentage combines 2PT shots, 3PT shots and free throw shots to come up with a single number that describes shooting accuracy.  I would rather keep ‘challenged’  (field goal) shooting separate from ‘unchallenged’ (free throw) shooting.  I prefer to use both eFG% and FT% as separate figures instead of lumping them all together as the TS% does.

Next article I’ll take a look at getting an accurate read on a player’s true rebounding ability.

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