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. 

Report: Rival teams expect Paul George to consider 1+1 contract with Thunder

AP Photo/Chris Szagola
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Paul George has openly stated the appeal of playing for his hometown Lakers. He has also openly stated the appeal of staying with the Thunder.

That has created significant confusion about his upcoming free agency.

Could George find a compromise outcome?

Marc Stein of The New York Times in his newsletter:

More than one rival team has suggested to me that they expect George to strongly consider a two-year deal with the Thunder at $30.3 million next season and $32.7 million in 2019-20 that includes a player option to return to free agency next summer.

This makes sense on paper.

A 1+1 contract would give George more time to determine whether he and Russell Westbrook can win together in Oklahoma City without getting stuck there long-term if they can’t. The Thunder were starting to put it together when Andre Roberson got hurt. Perhaps, Roberson getting healthy would swing Oklahoma City’s fortunes.

George would also be eligible for a higher max salary in two years – 35% of the salary cap, up from 30% if he signs now. So, a short-term contract would allow him to maximize his potential earnings.

But George said he wanted to sign somewhere long-term this summer. He also suffered an extremely gruesome leg injury just a few years ago. He might not want to bypass guaranteed money to gamble for a little more later.

Are these rival teams just looking at the general outlook for a player in George’s position without considering his specific circumstances? Or do they know something? George could have informed teams he might become available in 2019 or 2020 so they should prepare.

I’m skeptical this is more than speculation by opposing teams. But the possibility that they’re basing their expectations on inside information makes this worth monitoring.

Heartbreaking: Watch Mikal Bridges explain joy of joining hometown 76ers while they trade him to Suns (video)

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Mikal Bridges‘ mom jumped up, pumped her fists and screamed “Yes!” through her giant grin.

The 76ers – the organization she works for in human resources – had just drafted her son No. 10 overall. Bridges, a Philadelphia native who played at Villanova, seemed as if he’d stay home for his pro career.

Bridges:

She’s very, very excited. She’s been wanting this. She’s probably more excited than I am. She was about to cry and all that. She said she didn’t want to ruin her makeup, so she’d try to hold it in. But no, she’s very excited. I’m her only son. I’m a little mama’s boy. Her son is right there around the corner again, and it’s just really cool.

Except, as Bridges was talking, the 76ers were trading him to the Suns for No. 16 pick Zhaire Smith and the Heat’s unprotected 2021 first-rounder.

That extra pick carries major value. Even if you like Bridges much more than Smith – which I did, especially considering their fits in Philadelphia – that’s hard to pass up. The NBA is a business after all.

But it’s lamentable how this played out.

Kings GM Vlade Divac: ‘My team is a super team. Just young’

AP Photo/David Zalubowski
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The Kings drafted Marvin Bagley No. 2 last night (seemingly for bad reasons, which doesn’t at all eliminate him from being the right pick but makes it less likely he is). He’ll join a young core also comprised of Bogdan Bogdanovic, De'Aaron Fox, Buddy Hield, Willie Cauley-Stein, Skal Labissiere, Justin Jackson and Harry Giles.

That group excite you?

Kings general manager Vlade Divac isn’t reducing expectations.

Lina Washington of ABC 10:

To be fair, in 2012, the Warriors were coming off a 23-43 season with Stephen Curry and Klay Thompson already on the roster and had just drafted Draymond Green and Harrison Barnes. Everyone would’ve laughed at calling Golden State a “super team, just young” then. But those four (plus Andre Iguodala) eventually led the Warriors to a championship.

But, really: Nah.

Entering the 2016-17 season, then-Knicks guard Derrick Rose said, “They’re saying us and Golden State are the super teams.” We mocked Rose relentlessly, and of course, the Warriors went 73-9 while New York finished just 32-50.

How long until Divac’s young super team reaches even 32-50?

Spurs GM still optimistic relationship with Kawhi Leonard can be salvaged

Associated Press
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SAN ANTONIO (AP) — General manager R.C. Buford acknowledges star forward Kawhi Leonard is unhappy with the Spurs.

He remains optimistic the relationship can be salvaged.

Leonard has requested a trade from San Antonio because he is unhappy after missing most of last season with a right quadriceps injury. Buford would not comment on “speculation” of a trade demand, but agreed there is a fractured relationship between Leonard and the only franchise he has played for.

“Kawhi and his family mean a lot to the organization and to the community and while none of wish we are where we are, we’re going to do what we can to build the best relationship we can with him,” Buford said Thursday night as the Spurs made two late picks in the NBA Draft. “We’ll explore all of our options, but the first one would be to do what we can to keep Kawhi as part of our group.”

Leonard missed the first 27 games of the season but returned to play in nine games. He complained of discomfort and pain in the leg in his final game. Leonard sought an outside opinion after the Spurs cleared him to play, working with his own medical team in New York in an attempt to return to the court. The 6-foot-7 forward reportedly grew upset that the Spurs had questioned his rehabilitation process.

The Spurs listed him as out on their injury reports for much of the year citing “injury management.” While San Antonio was in the playoffs, losing in the first round to eventual repeat champion Golden State, Leonard was rehabbing in New York – which meant that Spurs coach Gregg Popovich, when asked for the situation, deferred all comment to “Kawhi and his group.”

“I think all of us would wish that things would have gone differently,” Buford said.

The Spurs held a team meeting late in the season where veterans, led by Tony Parker, implored Leonard to return. Leonard said he was unable to due to the injury.

In the 2016-17 season, Leonard averaged a career-best 25.5 points and was third in the MVP voting. The 2014 NBA Finals MVP and two-time NBA defensive player of the year is due just over $20 million next season, and can become a free agent in the summer of 2019. He is eligible to sign a $220 million extension with San Antonio.

He is reportedly willing to walk away from that to play elsewhere, possibly in Los Angeles.

“I don’t know that timing is a factor in this from today … he’s under contract for another year, our goal is to keep him as part of our program for a long time,” Buford said.