David Berri on Adjusted Plus/Minus

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Way back in 2006, David Berri, Martin Schmidt, and Stacey Brook came out with a book called The Wages of Wins. It was supposed to be Moneyball for sports other than baseball, but for a lot of people, the book read like Moneyball with a serious chip on its shoulder. In a team game with lots of variables, Berri and his co-authors were confident in their regression-based assertions that  there were 90 players more valuable than Allen Iverson during the season that he won MVP, that scoring was vastly overvalued while rebounding was too often neglected, and Ray Allen had been just as good throughout his career as Kobe Bryant. 

The general feeling among a lot of hard-core basketball fans and analysts was that the Wages of Wins system, which relied only on box-score based statistics, couldn’t possibly accurately capture everything that made a player valuable in a five-on-five game. The logical extreme of that philosophy came in the form of Wayne Winston, the former stat guru for the Dallas Mavericks whose brainchild was adjusted plus/minus, which sought to measure a player’s value without using any box-score statistics whatsoever. As it turned out, he had some even more outlandish conclusions than Berri and co. did. He said that the Knicks should never have traded Tim Thomas, that Lamar Odom was better than Kobe Bryant, and that Kevin Durant wasn’t helping the Thunder win. 
After last weekend’s Sloan stats and analytics conference, David Berri has a short post up on adjusted plus/minus. Here’s the crux of Berri’s argument for box-score bases metrics over adjusted plus/minus:
JC Bradbury and I – in a forthcoming article in the Journal of Sports Economics — report that only 7% of a player’s adjusted plus/minus is explained by what a player did the previous season (oddly enough, unadjusted plus/minus has a stronger – albeit still relatively weak – correlation).  In other words, the correlation coefficient for adjusted plus/minus from season-to-season is below 0.30.   And when we look at players who switch teams – as Songaila did – we fail to find a statistically significant relationship. In contrast, any measure (PERs, Wages of Wins measures, NBA Efficiency, Win Shares, etc…) based on the box score will have a correlation coefficient of at least 0.65, and often these marks are above 0.80. 

Berri makes a solid point. He uses Darius Songalia as a case study for how inconsistent adjusted plus/minus can be, but he could easily have used Kevin Durant, who started the season as a posterchild for how plus/minus based stats could contradict box score metrics but is now an example of how elastic adjusted plus/minus can be from season to season. 

I’m a big believer in using advanced stats to gain knowledge about basketball, but it appears that both Berri and Winston have holes in their metrics. Berri’s box-score based metrics don’t necessarily reflect who was doing what helped his team win the game. For example, let’s say Matt Barnes plays great defense on Kobe for 20 seconds and forces him into a tough fadeaway. Dwight Howard then blocks out Pau Gasol and keeps him from getting to the rebound. The ball caroms off the rim and goes to Vince Carter, who collects the easy rebound. In Berri’s system, only Carter gets credit for doing something right on that play. 
Winston’s system would theoretically give Barnes and Howard most of the credit for the play above. However, the issue is that they could have radically different roles on a different team. With another team, Barnes might not be a starter or a perimeter scorer, but a stretch four who provides energy and outside shooting off the bench without giving much on the defensive end. Thus, he could have a radically different value with a different team. 
Advanced statistics in basketball are wonderful, but they are far from airtight. For the foreseeable future, the best approach with advanced statistics will be to use a number of different metrics and see how they inform each other rather than wait for one perfect formula to reduce contributions to a single integer. 

WNBA team rehearses ring ceremony at practice of team it beat in Finals

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The NBA does petty very, very, very, very, very, very, very well.

The WNBA is trying to give the NBA a run for its money.

The Minnesota Lynx and Los Angeles Sparks have met in the last two WNBA Finals, the Lynx winning last year and the Sparks winning the year before. Minnesota hosted Los Angeles in the season opener Sunday, and the Lynx unveiled their banner and presented players with rings.

Before that, while the Sparks were practicing in Minnesota, the Lynx played their video for the event.

Holly Rowe of ESPN:

The Sparks beat the Lynx on Sunday, but I don’t think that’s enough to override Minnesota’s power move.

Kobe Bryant on Kanye West’s comments: “What the hell are you talking about?”

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Kanye West, the President Trump backing hip-hop star, drew a lot of backlash for his comments on TMZ:

“When you hear about slavery for 400 years — for 400 years? That sounds like a choice. You were there for 400 years and it’s all of y’all. It’s like we’re mentally imprisoned.” 

Mentally, maybe in some cases. But more so physically, with guns and whips and attack dogs and a whole lot more weapons that were all on one side. Nobody chooses slavery.

Tuesday, Kobe Bryant surprised a group of about 300 high school students at WE RISE — a 10-day pop-up festival dedicated to sparking a movement for change in the mental health system — in Downtown Los Angeles. One of the students asked him about Kanye’s comments. Kobe is not down.

“I’m sure (I feel) the same way everybody else here in this room feels. What the hell are you talking about? I think that was my reaction as is everybody else’s reaction….

“The thing about our country is that you have the right to say whatever it is that you want to say…that’s the beautiful thing about living in a democracy. I think, for him, he’s one of these entertainers that’s always in a constant state of growth, he’s always challenging … himself, doing a lot of questioning internally himself…so I just take it for what it is and completely disagree.”

If I need to explain to you why Kobe is in the right here, you need to take a basic American history course again.

Good on Kobe for his comments. More importantly, good on Kobe for taking the time to promote mental health awareness.

“It’s easy for us as people to kind of ignore the emotional side of it,  especially when it comes to things that deal with negativity, things that deal with insecurity, things that deal with fear,” Kobe said. “It’s very easy to take the fear and just push it down, try to act like it doesn’t exist. The reason why it starts with imagination is because you first must imagine the life that you want to have. You must first imagine what it is you dream of becoming.”

Kobe did that, and now he’s got an Oscar. Oh, and a few basketball awards, too.

PBT Extra: LeBron, Cavaliers even series but Celtics far from dead

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If you want to make the case that the Cleveland Cavaliers are in the driver’s seat of the Eastern Conference Finals after sweeping two games at home, you’re in a good space. It’s a best-of-three and Cleveland has the best player on the planet on their side.

However, I still like the Celtics to hold on and win in seven.

I get into it in this PBT Extra, but the Celtics looked like a team that figured things out in the final three quarters of Game 4 (they just couldn’t make up for a disastrous first quarter), and they still have two games at home.

Either way, this feels like a series going the distance.

Did the Warriors deal Rockets a knockout blow in Western Conference finals?

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The Warriors beat the Rockets by 41 (!) in Game 3 of the Western Conference finals Sunday.

Biggest playoff win in Golden State franchise history.

Biggest playoff loss in Houston franchise history.

Biggest playoff loss ever handed to any team as good as the 65-17 Rockets.

“At the end of the day, it’s one win,” Warriors forward Draymond Green said. “It doesn’t matter if you win by 40 or if you win by one.”

Maybe it matters more than Green is letting on.

Golden State was the 17th team to -win a playoff game by more than 40 points. Of the previous 16, 15 – including the last 14 – won the series:

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The only exception came in my favorite playoff series of all-time, the best-of-three 1956 Western Division semifinals:

  • Game 1: St. Louis Hawks 116, Minneapolis Lakers 115
  • Game 2: Minneapolis Lakers 133, St. Louis Hawks 75
  • Game 3: St. Louis Hawks 116, Minneapolis Lakers 115

So, teams to win a playoff game by more than 40 are 15-0 in best-of-seven or best-of-five series. Will the Rockets buck the trend?

They can make adjustments. Maybe Houston’s strong regular season – better than any above blown-out team’s – indicates a rare capability to recover from this. Andre Iguodala‘s injury hurts Golden State. Teams sometimes make historic comebacks from blowouts, including against the Warriors.

But that Golden State ran toppled the Rockets so decisively in Game 3 suggests the Warriors are hitting a gear Houston won’t keep up with.