Introduction to Player Value: An Overview of HOOPWAR

Imagine my surprise this morning when I got a Google Alert for my name and it was another SBNation site writing about HOOPWAR.

The guys over at At The Hive stole my thunder a little bit, but I still wanted to write an introductory post to our player evaluation formula. No formula is perfect. That standard is almost impossible. Maybe with advanced statistics that the teams gather on their own players, you could combine everything into some super formula.

But this seems good. It is repeatable. As far as I know, it passes the eye test. And it generates results that make you think about how you look at basketball.

What more could you ask for?

The origins of HOOPWAR are here, along with a long explanation of why I choose each of the components of the calculation.

The formula in its simplest is this:

(Points Saved + Points Earned) * Average Pace/Team Pace 
  - Replacement level / 30.

To go a little deeper:

Points Saved = (Defensive Rebounds + Steals + Blocks - Fouls) 
  * Team defensive points per possession

Points Earned = FG * (2 * (1-TeamAstPct)) + 3PT * (1-(Team3ptShotPCT*TeamAstPct))+ FT 
  + Off Reb + Ast * TeamAstPct * ( 2+Team3ptshotPct) - 
  ( TO * Team offensive Pts per Possession)

I think that most of the numbers here are self-explanatory. The one that might need a little help is TeamAstPct which is the percentage of baskets by a team where there is an assist.

That will give you a raw score for what a player is worth in terms of points during a season.

We take that number and normalize it based on the pace of the game that the player's team plays so that every team is on equal footing. We don't want speedsters that play 40 minutes of hell tearing up the charts compared to Wisconsin's big men.

Finally we subtract out the value for a replacement player. This was based on how a team of replacements would do over the course of a 30 game season. It basically comes down to a replacement player being worth 160 points per 500 minutes played. Most replacements never play that much (although you would be surprised at how many players worth about as much do play that many minutes).

The amount subtracted from the adjusted points is a percentage of the replacement player (or a multiple) based on how many minutes a player has been on the court during the season.

Finally we divide by 30 which is about the point differential value of a win in college basketball.

I used the Pythagorean Formula for basketball to approximate a team's winning percentage using points scored and points against. The exponent in the formula varies, according to posts I have seen. I used 10.45. At that exponent, it take a marginal change in points of about 30 to "earn" an extra win.
At the upper levels of the formula, it gets hard to move that needle, but that is why it is very difficult to win 100 percent of the games.
So much like 10 in baseball, I divided the total by 30 to get what I am calling HOOPWAR.

For comparison purposes, I have been normalizing these values again to what would be a 30 game value for each player.

As I mention in the post over at MRISports, there are a few things about the formula that could be issues: the defensive calculation, the value of replacement level, and the "total" problem. Yet I think that the benefits of the formula in many ways outweigh the questions that I still have.