The second post of a series used explaining the statistics that have and will be used on this site, noting their strengths, shortcomings, and how they apply to the Knicks. (Intro)

Creating advanced statistics intended to stuff all facets of a player’s worth into a single figure is like cooking with a complex recipe. Striking the right balance in ingredients is the most important, yet difficult part. Some may think more of this, less of that, and none of the that. Oft-used statistics such as John Hollinger’s Player Efficiency Rating (PER), David Berri’s Wins Produced (WP48) and Win Score, and NBA Efficiency are all examples of linear weight systems. In other words, they aggregate a number of statistics and apply a certain factor to them, but these inherently leads to disagreement among linear weights advocates and the resulting multitude of linear weights systems.

Adjusted plus/minus, meanwhile, is like making toast. You have two ingredients, offense and defense, the latter of which is not included in the linear weights systems, and there is a set ratio (1:1) between the two that isn’t up for debate. Defense is half the game, and the ability of adjusted +/- to incorporate it adequately has lead to the statistic being the most used by NBA front offices. The Cleveland Cavaliers, Houston Rockets, Dallas Mavericks, Portland Trail Blazers, Oklahoma City Thunder, Memphis Grizzlies, and Boston Celtics all employ some statistics savant to decipher adjusted +/- numbers for them, because they can reveal a whole damn lot.

What is it, exactly? Adjusted plus/minus is a souped-up version of basic plus/minus, which is the net points gained or lost when a player was on the court. Turning basic +/- into adjusted +/- is the equivalent of transforming your Kia into a shiny Lamborghini – right to the cream of the crop. Two of the statistic’s creators (it was “discovered” multiple times, independently) describe it here, but in essence, it is a total measure of a player’s effect on point margin that takes into account a player’s surroundings. The knock against basic +/- is that the number is inflated when on the court with a fantastic player, deflated with bad player, etc. Using a regression, adjusted +/- normalizes all players on the court, so Joel Anthony will not be rewarded for being on the court with Wade/Bosh/LeBron, and a player opposing that trio will not see an exaggerated dip in his adjusted +/-.

Beyond individual ratings, however, adjusted plus-minus scores can be accurately applied to lineups and are utilized primarily for this reason by teams. Adjusted +/- ratings can be brought up for an entire five-player unit, how that unit did against another unit, how one player did against another unit, how a pair of players did with each other, and how a player did against another player.

Top 10 in ’09-10: Dwight Howard, LeBron James, Kevin Durant, Dwyane Wade, Steve Nash, Chris Andersen, Deron Williams, Andrew Miller, Ray Allen, Al Horford (via BasketballValue.com)

Pros:
- No debate over variables (there are none)
- Equal representation for defense
- The only, truly “total” statistic
- Able to translate activity off the ball into easily interpretable numbers
- Great value in lineup analysis
- Minimal disagreements among adjusted plus/minus providers

Cons:
- Severe fluctuations from year-to-year (Durant in 08-09: -8.62, Durant in 09-10: 17.75)
- Generally requires over 1,000 minutes of data
- Two year adjusted +/- ratings yields the most accurate results
- Pain to calculate (requires detailed play-by-play data)

On the Knicks: In limited time, Bill Walker led the team with a +4.82 rating, followed closely thereafter by Danilo Gallinari (4.35). Walker had just 768 minutes under his belt, so his figure may be a product of a small sample size and due to digress. Perhaps a result of his defensive shortcomings, David Lee was near the bottom of the list with a -3.77 rating, actually worse than Nate Robinson and Larry Hughes (granted, both had limited minutes). Jared Jeffries had the third-best rating.

How should it be used? To me, there are better measures of offense available by using either PER or Wins Produced, but adjusted plus/minus comes in handy most when attempting quantify a player’s defense and play off the ball. For example, Shane Battier, a top defender, has a good +/- rating, but is virtually a zero as far as scoring is concerned. When I have written about Carmelo Anthony, I have repeatedly said that production does not match ability. Just like for all statistics, it is important to remember that they can often be improved on. Carmelo’s +/- rating is decent in relation to his reputation, but does that mean it will never improve? No.

Links: BasketballValue.com, Wayne Winston, 82games.com

Tweet Photo: Nathaniel S. Butler/NBAE via Getty Images