Effective Free Throw Percentage

BV recently posted an interesting discussion about the effect of percentages on fantasy performance over at Fantasy Basketblog. That was a follow up to an earlier discussion on the same topic by DM. Both are good reads and I would recommend that you take a look at those discussions before reading any further.

The last paragraph of BV's discussion really caught my attention.

See? It took me almost 1,000 words to better gauge the fantasy values of just a few guys. And even then, it’s not an exact science. I can’t tell you if Eddy Curry or Tim Duncan is worse – or if Jason Williams or Paul Pierce are more valuable from the stripe. The player raters are a good guide but they are by no means the final word. If you’ve got your own way of valuing FT%, we’d love to hear it. Hope this helps.

Well, it just so happens that I've been experimenting with ways to accurately measure the fantasy value of percentages. While BM is right, this is no exact science (unlike something as rock solid as intelligent design) I've come across a pretty decent way of measuring percentages. For the sake of this post, I’ll call it Effective Free Throw Percentage, not to be confused with the already mysterious Shooting Efficiency.

The answer is to weight a player’s free throw (or field goal) percentages against the league average. Now league average is a pretty nebulous concept, but after ranking fantasy players through this point of year, I took the top 150 to use as my “league”. Number 149 is Deron Williams and 150 is Kevin Martin, so I think the lower bar is set about right for most leagues out there. The formula for EFT% is:

EFT% = FT%lg + (FT%p – FT%lg) * (FTAp/FTAlg)

Where,
FT%lg is equal to the league average Free Throw Percentage (76.3%)
FT%p is the Free Throw Percentage of the player
FTAlg is the league average number Free Throw Attempts (4.2 attempts per game)
FTAp is the number Free Throw Attempts of the player

So, Effective Free Throw Percentage weights the difference between the player’s percentage and the league average and adjusts the result by the difference in the player’s free throws attempts compared to the league. It basically places player’s free throw percentage on a level playing field with all other players. This stat can be calculated either on season or per game stats. I have calculated it per game.

On to the fun stuff. The top 10 EFT% leaders so far this year.

Name	FTA	FTP	EFT%	DIFF
Chauncey Billups	6.4	92.7	101.4	8.7
Corey Maggette	8.9	87.1	99.3	12.2
Dirk Nowitzki	7.2	88.9	98.0	9.1
Steve Nash	4.1	93.6	93.2	-0.4
Michael Redd	7.7	84.9	92.1	7.2
Kobe Bryant	10.5	82.5	91.9	9.4
Ray Allen	4.6	90.1	91.5	1.4
Vince Carter	7.7	83.6	89.7	6.1
Caron Butler	5.5	86.5	89.7	3.2
Peja Stojakovic	3.4	92.6	89.5	-3.1

First off, it IS possible to have an EFT% over 100. Basically, if Chauncey Billups shot the league average number of free throws per game, he would have to make 101.4% of them to have the same effect on your team. That is quality you can take to the bank. In fact, Billups, Corey Maggette, and Dirk Nowitzki are leading the pack by a huge amount – almost 5 percentage points. DIFF is the difference between a player's actual free throw percentage and his EFT%. Only two players in the top 10 have an EFT% below their actual; Steve Nash and Peja Stojakovic. So, to be part of the best, it helps shoot a lot of free throws and shoot them well.

And now the even funner stuff. The players with the lowest EFT% so far this year.

Name	FTA	FTP	EFT%	DIFF
Shaquille O'Neal	7.2	44.1	20.9	-23.2
Darius Miles	6.9	55.3	41.7	-13.6
Ben Wallace	4.3	47.7	46.9	-0.8
Ron Artest	7.6	61.2	48.9	-12.3
Dwight Howard	6.5	59.4	50.1	-9.3
Jamaal Magloire	4.4	54.3	53.2	-1.1
Chris Andersen	3.1	47.7	55.1	7.4
Eddy Curry	6.8	63.5	55.5	-8.0
Alonzo Mourning	3.4	54.3	58.4	4.1
Ruben Patterson	5.2	62.2	58.8	-3.4

As brought up by BV, the bottom is filled up with (mostly) big men. Shaq – as in most aspects of his life – appears to be in a class by himself. His EFT% is twice as low as anyone else on this list. Darius Miles, Dwight Howard, and Eddy Curry are all negative affected by the high number of free throws they take. Ron Artest, who has never been mistaken for a good free throw shooter in his career, has been particularly bad in the games he’s played in. But – at least he has plenty of time now to work on his shot, or maybe a new rap album.

And to answer the original questions posed by BV which got me thinking about this question; Eddy Curry (EFT% of 55.5%) is worse for your team than Tim Duncan (60.9), Paul Pierce (83.2) is having a slightly better year than Jason Williams (80.7), and Chauncey Billups is still the man.