PDA

View Full Version : A different way of measuring an NBA player's worth


JAG
04-13-2004, 04:45 AM
Not sure if others have heard of this, but it seemed pretty interesting to me. It seems like more math / stat geeks are coming out with publications on sports these days, such as the one some university prof did proclaiming more NFL teams should go for it on 4th down situations (he didn't take into account non-stat factors such as momentum, home/away, and so on into his study however). This system seems a lot more reasonable to me, especially when the article mentions Isiah Thomas wasn't interested in it. :)

Numbers game

By Patrick Hruby
THE WASHINGTON TIMES

Everyone else has it wrong. The fans. The press. Even the league. They're blinded by box scores. Hamstrung by hype. Of this and more, Wayne Winston is certain. A single mouse click tells him so.

"Nobody should be talking about LeBron James and Carmelo Anthony," he says. "They should be talking about Dwyane Wade. It's a crime."

For Winston, Wade's superiority is not a matter of opinion. It's a fact, cold and hard, like an icicle. You can argue politics, and you can argue the best "Godfather" flick (well, excluding part III). But when it comes to the NBA Rookie of the Year race, you can't argue the data. At least not with Winston, a former "Jeopardy" champ who's good with math the way Eric Clapton is good with chords.

"James rates as an average NBA player," says Winston, a professor of decision sciences at Indiana University. "That's good since very few rookies rate that high. But Wade's a real impact player for Miami. He ranks 21st best in the league in terms of changing the chances of your team winning a game."

Like any MIT graduate worth his sodium chloride, Winston has the numbers to prove his point. More than 5,000 pages' worth, to be exact. Only you won't find his statistics in a newspaper. Together with fellow sports math guru Jeff Sagarin — the brain behind USA Today's computer rankings — Winston has created Winval, a sophisticated program that rates and ranks the value of every NBA player from Tariq Abdul-Wahad to Lorenzen Wright.

Used by the Dallas Mavericks, the system ignores traditional measures like assists and rebounds to answer a more basic question: Namely, does a team play better or worse when a particular player is on the floor?

"We don't care if you never score a point," Winston says. "If you make plays and help your team win, you don't have to score."

If it sounds a bit like the stats-centric, counterintuitive "Moneyball" revolution sweeping through baseball, that's no coincidence. The idea is the same: use the mathematical tools of quantitative analysis to go beyond the box score and discover the hidden factors that contribute to victory.

On the diamond, that means dumping sexy batting averages for dowdy on-base percentages; on the hardwood, it means focusing less on points per game and more on exotic measurements like the aforementioned "impact" rating.

"You couldn't run a team completely on statistics," Indiana Pacers general manager Donnie Walsh says. "But anybody from the old school who doesn't pay attention to them is probably in the wrong. Everyone's looking for an edge. And this kind of information can give you one."

Can it ever. In a recent Dallas-Miami contest, the Mavericks were outscored by a total of 17 points during the times a particular Mavericks player — who won't be named here — was on the floor. During the times that same player sat on the bench, the Mavericks were a cumulative plus-16.

The Heat won the game by a point.

"That's important information, but you wouldn't know it because the guy came in and out eight or nine times," Winston says. "The game moves so fast that unless you have somebody tabulating this and analyzing it properly, you're just not going to know. A lot of coaches think they know more than they do."

Four years ago, Winston took his son on a spring break trip to Dallas. Sitting in some choice seats at a Pacers-Mavericks game, they ran into Dallas owner Mark Cuban, a former student in Winston's statistics class.

"We shook hands," Winston says. "He asked me, 'Do you have any way to make the Mavs better?' "

As he unwound in a hotel pool the next day, Winston had an epiphany: If entire teams could be rated and compared, then why not individual NBA players?

Winston ran the concept by Sagarin, a close friend since their days as fellow MIT undergraduate math majors. They settled on a variation of hockey's plus-minus system, in which players are judged by how well their team plays while they are in the game.

In the NHL, for instance, a player who is on the ice when his team tallies a goal earns a rating of +1; if the team yields a score, that same player would receive a -1 mark.

"Basketball's a team sport, and lots of things aren't tracked," Winston says. "Like taking the charge, going through a screen, tipping a ball to your teammate, saving a ball from going out of bounds. That's where our system comes in. All these little things should translate into points."

One problem: Traditional plus-minus systems tend to overrate average players on good teams and underrate good players on lousy ones. After all, a zero plus-minus rating on the Los Angeles Lakers is not the same as a zero rating on the Los Angeles Clippers, mostly because one team has Kobe Bryant and Shaquille O'Neal and the other has Marko Jaric and Chris Kaman.

To compensate, Winval's ratings are weighted to take into account every other player on the floor. For every time segment a player is in a game, the system tracks the other nine players on the floor, the length of the segment and the score at the start and end of the segment.

The result of all that math? Rankings that sometimes refute conventional NBA wisdom. High-scoring players like Vince Carter, Dirk Nowitzki and likely MVP winner Kevin Garnett are among Winval's top 10. But so is San Antonio's Bruce Bowen, an unsung defensive specialist who averages just 6.8 points a game.

On offense, Bowen makes the defending league champs less than a point a game better than an average NBA player. On defense, however, the Spurs are 10 points a game stingier with Bowen on the floor.

Sacramento's Brad Miller and Denver's Nene fare well for similar reasons, while the Nuggets' Anthony, the Kings' Mike Bibby and New York's Stephon Marbury rate lower than you might expect.

"Marbury's one of the top 10 players on offense," Winston says. "Everybody thinks this guy is a great player. But when he's on defense, he gives it all back."

Before every Dallas game, Winston and Sagarin sift through a 38,000-row spreadsheet of raw data, then send a customized scouting report to Mavericks assistant coach Brian Dameris. Each report contains a list of hot and cold players for each squad, drawn from individual Winval ratings over the previous five games.

Two weeks ago, for example, Golden State's Mickael Pietrus ranked as the league's third-hottest player; not coincidentally, the seldom-used rookie averaged 14.2 points and 30.3 minutes over a six-game stretch, far better than his season averages of 4.7 points and 13.3 minutes.

Had the Mavericks played the Warriors, the Mavericks would have known to give Pietrus extra defensive attention. Conversely, cold ratings can tip Dallas off to struggling or injured opponents.

A few years back, Winston couldn't figure out why Jason Kidd's normally stellar rating had taken an abrupt nosedive. It later came out the All-Star guard had been involved in a domestic altercation with his wife.

"DeShawn Stevenson, on Utah last year, his rating was really bad for two weeks," Winston says. "The next week, I found out he was suspended from the team. So we can spot these guys having problems. We don't know if they're marital, psychological, injuries. But if a guy starts playing [bad], we know it. And the Mavs go at him."

Of particular use to the Dallas coaching staff is Winval's "lineup calculator," a software tool that measures the effectiveness of various player combinations on a game-to-game, weekly and season-long basis.

According to the system, Nowitzki and Eduardo Najera make up one of the Mavericks' top frontcourt pairings, while an on-floor five of Nowitzki, Michael Finley, Steve Nash, Antoine Walker and Scott Williams is 25 points better than an average NBA lineup per 48 minutes.

During last year's playoffs, Winval indicated Shawn Bradley was more effective facing Portland than Sacramento. The Dallas center started six first-round games against the Blazers but played sparingly vs. the Kings in the conference semifinals.

"If you're a coach and you're watching the game, you might not pick all that up," says Seattle SuperSonics assistant general manager Rich Cho, a former Winval user. "After the game, you might look at the box score and see a player has good stats. But it's hard to correlate that with who he was on the floor with."

Last summer, Winston and Sagarin met with Walsh, whose Pacers were upset by Boston in the first round of the playoffs. In splitting the first two games of that series, Indiana fielded a particular lineup that had a plus rating of nearly 50.

Over the next three games, however, that lineup barely played.

"When we showed that to Donnie, his eyebrows nearly flew off his forehead," Sagarin says.

Though Walsh was intrigued, then-coach Isiah Thomas expressed little interest in the system. Cuban says he's often mocked for using Winval. Cho notes that veteran scouts and coaches aren't always comfortable with new school number-crunching.

"People see it as some kind of threat to the old school way of thinking," Walsh says. "I don't see it that way. I think one helps the other. It's a digital world."

Like any mathematical model rooted in human behavior, Winval has its limits. Highly rated players can suffer bad stretches (Winston calls it the "girlfriend" factor). Trades often produce significant rating fluctuations.

Winston says he can predict a player's future rating within four points but only about 60 percent of the time — not good enough for Cuban, who has used the system to help evaluate roster moves.

"The information is a good reference point, but unlike 'Moneyball,' where there are definable variables that enable a team to select players wisely, there are no such variables identified yet in basketball," Cuban says. "Personally, I think it's because we don't collect the right data."

Still, Cuban is happy to pay for use of the system, which can cost up to $30,000 a month. The Mavericks also track referee tendencies — and not simply as part of the owner's ongoing effort to make league officials more consistent and accountable.

"Jermaine O'Neal leads the league in offensive fouls," Winston says. "If you have three refs on the court who call lots of charges, then when Jermaine throws an elbow, fall down."

Meanwhile, Winston and Sagarin continue to tweak their brainchild. The latest stat? "Impact" rating. Basically a measure of clutch play, it compares a team's probability of victory when a player comes into a game vs. the team's odds of winning when the same player comes out.

According to Winval, Houston's Yao Ming leads the league in impact. Also in the top 10? Cleveland's Carlos Boozer, whose +29 rating is nearly three times higher than that of James.

"Cleveland is better this year because of Boozer," Winston says. "James is nice, but he's not the main reason."

Which again brings up the rookie of the year debate. On the floor, Miami is surging past Denver and Cleveland; on the screen, Wade has a +25 impact rating, tops among rookies and much better than either Anthony (-7) or James (+3).

Do the math, Winston says. The choice should be clear.

"Wade is a really solid player," he says. "But he probably won't win. He doesn't have the pedigree. There are 100 articles on LeBron to every one on Wade."

True enough. Even when everyone else is wrong, some numbers can't be argued with.

Alf
04-13-2004, 06:10 AM
Interesting read. And makes sense, though I am an old school basket-ball guy.

RPI-Fan
04-13-2004, 07:00 AM
I definitely agree with this. Too many "stars" are great on the ball offensive players, but do absolutely nothing else - Marbury and Anthony, and to an extent James.

GrantDawg
04-13-2004, 07:36 AM
Like any mathematical model rooted in human behavior, Winval has its limits. Highly rated players can suffer bad stretches (Winston calls it the "girlfriend" factor)...
Sounds like Jim wasn't too far off with the girlfriend thing. :D

Subby
04-13-2004, 07:51 AM
I absolutely love this...it should put to bed once and for all the notion that Jerry Stackhouse is a good player.

JAG
04-13-2004, 07:54 AM
I thought it would be interesting to see something like this for football, but I think other sports would be a whole lot more difficult than basketball, if it would even be feasible at all.

cthomer5000
04-13-2004, 08:26 AM
I thought it would be interesting to see something like this for football, but I think other sports would be a whole lot more difficult than basketball, if it would even be feasible at all.
It might be next to impossible for football. With both personnel and the situation dramatically changing from play to play, there might be too many variables.

MikeVic
04-13-2004, 09:01 AM
My question is: who is the Mavs player that made the team a -17 during that stretch?

j51
04-13-2004, 09:15 AM
My question is: who is the Mavs player that made the team a -17 during that stretch?

http://sportsillustrated.cnn.com/images/basketball/nba/players/3112.jpg

Antoine Walker

RPI-Fan
04-13-2004, 09:16 AM
Michael Finley is my guess.

QuikSand
04-13-2004, 09:23 AM
Aspiring gearheads should focus in on one particular stat from this article:

Still, Cuban is happy to pay for use of the system, which can cost up to $30,000 a month.

That's what I'm talking about!

cthomer5000
04-13-2004, 09:28 AM
yeah, that does seem a bit steep for a pretty unproven system. I guess Cuban has money to burn though.

KWhit
04-13-2004, 09:31 AM
Aspiring gearheads should focus in on one particular stat from this article:



That's what I'm talking about!
I thought the same thing, QS.


"Now why didn't I think of that?"

Oh yeah, I didn't go to MIT.

sterlingice
04-13-2004, 09:49 AM
Sounds an awful lot like they just copied Bill James's win shares and modified it for basketball. Or, at least the concept is the same even if the numbers going in are very different.

SI

Huckleberry
04-13-2004, 09:52 AM
I disagree with Cuban on the problem with the basketball version. Baseball is much more ready-made for these kind of analyses. The reason?

Baseball is played in series. Basketball, football, hockey, soccer, etc. are all played in parallel. On any given play in baseball you have the pitcher making the pitch, the batter choosing to swing or take, the batter swinging, the ball either being missed or put in play, the fielder making a play, the fielder making a throw, another fielder making a catch, etc. All of these things happen in order, one at a time. The only things that happen in parallel in baseball are baserunning/fielding and fielding/positioning. And you'll notice that there aren't good stats yet for baserunning. Nobody cares about stats (if one could be created, which seems unlikely) for infield positioning for throws from the outfield or elsewhere on the infield. That kind of positioning is done pretty much the same by everyone.

When you have a series of individual performances like that, it makes it much easier to calculate the effectiveness of each player.

Meanwhile, the other sports have everyone on the field contributing to every play the whole time the play is happening. It is almost impossible to calculate each person's contribution to a football play. Whereas solving for the individual values of components in an electrical circuit that are positioned in series is relatively simple while for components in parallel it is relatively difficult, statistical analysis of the one sport played in series has proven very difficult while statistical analyses of the sports played in parallel seems on the verge of impossible.

JeeberD
04-13-2004, 02:31 PM
http://sportsillustrated.cnn.com/images/basketball/nba/players/3112.jpg

Antoine Walker

That would be my guess as well, though I was surprised to see that he was on the Mavs "best squad".

QuikSand
04-13-2004, 02:35 PM
Oh yeah, I didn't go to MIT.

*sigh* Me, neither.

rkmsuf
04-13-2004, 02:39 PM
The guy is a genius just for getting 30K a month for this stuff.

Samdari
04-13-2004, 02:45 PM
The guy is a genius just for getting 30K a month for this stuff.

He's getting paid that by a guy who is rich because he:

1) Started with an idea, and started a business worth nothing.
2) Built this business into an entity worth, well, nothing.
3) Sold this business worth nothing for $1 billion dollars.

I wish I were Mark Cuban. I have lots of ideas that could lose money.

HornedFrog Purple
04-13-2004, 02:48 PM
yeah... he bought a franchise that was worth nothing and the laughing stock of sports and has quadrupled their net value.

what an idiot.

Samdari
04-13-2004, 02:52 PM
I was not saying he was an idiot - I was seriously saying he was brilliant for convincing someone to give him a billion dollars for a franchise which had never - nor would ever - make money.

Barkeep49
04-13-2004, 03:04 PM
Being a fan of quantative anaylsis this seems great and I wish there was more information presented about how exactly it works with the other 9 players on the floor. In terms of my own coaching would that normalization even matter? I obviously don't have the capabilities of figuring out the plus/minus other teams because the scouting just isn't there, so would doing the plus/minus help figure out the best group of players I could put on the floor or would it be worthless without the normalization?

Does what I'm asking make any sense?

Desnudo
04-13-2004, 03:07 PM
"A different way of measuring an NBA player's worth "

I thought the answer was going to involve kilos and grams.