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Tuesday, February 7, 2012
Updated: August 13, 3:21 PM ET
On the plus side

By Peter Keating
ESPN The Magazine

Mavericks
Carlisle and the Mavs used plus/minus to rest Dirk and exploit good matchups.

This story appears in the Feb. 20, 2012 "Rivalry Issue" of ESPN The Magazine. Subscribe today!

OVER THE PAST DECADE, basketball statheads have hotly debated a metric that sabermetrician Tom Tango calls a With or Without You stat: plus/minus. Plus/minus looks at a team's point differential when a player is on the floor compared with when he's not. In theory, this is a clever way to measure not just a player's scoring but something media types love: the so-called intangibles. For example, when the Sixers beat the Pacers 96-86 on Jan. 9, Thaddeus Young had only 12 points, but he deflected five passes, took four charges and was plus-16 on the night, the highest figure for any player in Philly's win. Plus/minus captures the impact of great defense, selfless offense and every other hidden contribution that can change the course of a game.

So what's the issue? Well, a player's plus/minus score bounces around a lot from night to night, so you can't use it to evaluate a guy after just a few appearances. "You look at a partial season of plus/minus and you can't tell if a guy is Patrick Ewing or Keith Bogans," says one NBA GM. The stat is hugely influenced by other players on the court too. Chris Bosh plays with two future Hall of Famers, so his plus/minus looks great. John Wall's Wizards routinely get crushed, so his looks awful.

But these features don't mean the stat is worthless, as some in the APBRmetrics community would have you believe. (APBRmetrics is the term for hoops sabermetrics, derived from the Association for Professional Basketball Research.) Dallas revealed in its title march last season that plus/minus can be repurposed for a far loftier goal than evaluating individual play -- it can be used to identify winning lineups.

Unlike baseball, in which discrete stats matter most, basketball is a fluid, all-on-all sport in which teammates affect one another. And some players perform so well (or poorly) with certain partners and against particular opponents that you can see the effect in plus/minus, even in small sample sizes.

Consider Orlando's Jason Richardson and Ryan Anderson. If you add up their individual plus/minus scores from last season, the total would have ranked 168th among all two-man combos. But when they played together, they added 2.1 points per 100 possessions to the Magic's offense, according to Jeremias Engelmann's plus/minus calculations (stats-for-the-nba.appspot.com). That made them the sixth-best duo in the NBA. Now, this doesn't tell us how good Richardson or Anderson is on his own, but it strongly suggests they should play more minutes together.

The Mavericks, more than most teams, appreciate the right matchups at the right time. This is, in fact, how they won the title last season. Down two games to one against Miami, Rick Carlisle, with advice from Mavs statistical guru Roland Beech, started J.J. Barea at guard in place of DeShawn Stevenson. Overall, Barea wasn't playing that much better than Stevenson, but the Mavs knew Barea had been plus-17 in 33 minutes against lineups that included Miami starting point guard Mike Bibby, according to plus/minus mastermind Wayne Winston (waynewinston.com). Facing Bibby, Barea helped spark the Mavs to wins in Games 4 and 5.

Carlisle also found a way to rest Dirk Nowitzki during the series without getting punished. Through Game 3, the Heat outscored the Mavs by 31 points when Nowitzki sat, largely because Miami manhandled Peja Stojakovic (minus-21). So as the series pressed on, Carlisle started using Brian Cardinal instead -- and the Heat didn't adjust. In Game 6, Stojakovic played zero minutes, while the Dirkless lineup of Jason Terry, Shawn Marion, Tyson Chandler, Jason Kidd and Cardinal was plus-10. The Mavericks won the Finals' decisive game by 10 points. "Chess in sneakers beat hero ball," wrote Jeff Fogle of Hoop Data (hoopdata.com).

Team-level plus/minus is often revealing even when you think you know everything about a club. This season, for example, amid all the chatter about whether Carmelo Anthony and Amar'e Stoudemire can play together, the Knicks' more troublesome combo is Anthony and Bibby. When they were on the court, through Jan. 25, New York was outscored by 24 points every 48 minutes, according to Basketball Value. Next time Knicks fans see that duo on the floor, they should start screaming. And if Mike D'Antoni wants to keep his job, he may want to listen up.

Peter Keating is a senior writer for ESPN The Magazine. Follow The Mag on Twitter, @ESPNmag, and like us on Facebook.