The Strengths and Weaknesses of Plus-Minus

Given small sample sizes (one game being the smallest), plus/minus is an interesting, yet seriously flawed statistic, in that it is exaggerated by the ebbs and flows of the game. One team goes on a 12-0 run over two minutes of game action, and suddenly the five guys on the floor at that time are statistically punished. It's impossible to determine how much blame each of the five guys deserve in that two-minute span. One can argue that the weakest defender on the court is usually a part of the opposing team's biggest run, but what about the other four guys? Plus/Minus does a better job of evaluating performance over an entire season, as the ebbs and flows will tend to balance out. More on the 2012-13 Plus/Minus Leaders/Losers below.

With most players, their inability to play defense shows up in the plus/minus category. My instinct would be to say the worst plus/minus guys are probably coming off the bench for the worst defenses in the NBA. Here's a look at the Low-20 of the year.

Through February 24th, the minus leaders (or losers) of the NBA season (minimum 40% of team's minutes) are:

• Phoenix's Markieff Morris and Austin Rivers at minus 9.2.

Morris' biggest strength was supposed to be his range, which Phoenix hoped would create match-up problems by inserting him at power forward. After November's 38% shooting, Morris has fallen apart. On the season, he sits at 29%. His inability to guard opposing power forwards or to rebound, have resulted in a disastrous season. Morris' opponents production rating is the highest in the league (23.2), making him arguably the worst defender in the NBA. Phoenix is 23rd out of the 30 NBA teams in defensive efficiency, which means it's likely other Suns should be in the Low-20. In fact, Michael Beasley is 6th-worst at minus 7.0. Notably, Markieff's twin brother, Rockets power-forward Marcus, is also on this list, coming in at minus 4.3. Guess their parents never explained the value of protecting the rim, or going after the ball with Faried-like tenacity.

Doc's own son, Austin Rivers has had a horrifying rookie season. Rivers' issues are more with the scoring side. Basically, he can't put the ball in the hoop. A pathetic 4.9 rating (only two other NBA players are under 10--Shane Battier and Kevin Seraphin at 9.4 and 9.5) is one of the reasons you might be hearing that Austin Rivers' season is not just bad but historically bad. Looks like Austin is exhibit A for staying in college more than one year. New Orleans is 28th in team defensive efficiency.

• Boston's own Brandon Bass is third-worst in the league at minus 8.6.

Every time you watch a Celtics game, you might wonder how much better the Celtics could be this season if Jared Sullinger had remained on the court. Sullinger was a staggering plus 66 after 35 games this season. Chris Forsberg's piece on KG's impact on Sullinger is here. As Celtics fans know, Bass can't shoot the way he did last year. Like Morris, Bass is an undersized power forward who cannot defend or rebound against the bigger and more athletic 4's. When Bass is off the court, the Celtics are plus 6.o on the season, most of which came from Sullinger. We have to hope that Sullinger is able to make a complete or near-complete recovery and the back issues don't become career-defining the way most GM's feared on draft day last June. As a side note, the Celtics leaders in plus-minus are: Garnett 5.4, Pierce at 3.8, and Jeff Green also at 3.8.

To read the complete post, click here: http://darkoindex.com/2013/03/14/the-strengths-and-weaknesses-of-plus-minus/

Thanks for reading and Go Celtics,

Jonah