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. 

Portland’s Jusuf Nurkic undergoes surgery to repair leg, full recovery expected. Eventually.

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As expected, Jusuf Nurkic underwent surgery on Tuesday repair the frightening leg injury he suffered on Monday night, a fractured left tibia and fibula that left his leg bending in a way that no leg should ever bend.

The good news is the surgery went as well as could be hoped, according to the team and Shams Charania of The Athletic.

Even with a successful surgery, this is going to take a long time to come back from.

As Jeff Stotts of In Street Clothes noted, the only comparable injury like this in the NBA was Paul George‘s frightening leg injury with Team USA. George made a full recovery, but it was eight months before he got back on the court and much longer until he was comfortable enough to be the MVP candidate he is this season.

Nurkic had made a leap this season, averaging a career-high 15.4 points per game this season on 50.7 percent shooting. The advanced stats loved him — his PER of 23.1, true shooting percentage of 57, value over replacement player of 3.5, and other advanced stats are all career bests. He was the anchor in the middle of the Portland defense, using his big body to cut off drives on pick-and-rolls. He was serving as a playmaker on offense: When he’d set a high pick for Damian Lillard, teams would trap the guard, Lillard would pass to Nurkic, and the Bosnian had become a good passer or he just take it in and scores himself

All of that came after Nurkic signed a four-year, $48 million contract extension last summer.

His injury also devastates the Blazers heading into the postseason, where they could have been a tough matchup but have now lost a key piece of their puzzle.

 

Celtics’ Kyrie Irving to rest against Cavaliers, his former team

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CLEVELAND (AP) — Kyrie Irving said returning to Cleveland tonight won’t mean anything to him.

He won’t even play.

The Celtics will rest rest the star against his old team, the Cavaliers.

Irving is averaging 23.8 points and the Celtics want to keep him as fresh as possible going into the postseason.

The Celtics have lost four straight and are fifth in the Eastern Conference entering Tuesday night’s game in Cleveland.

Irving played his first six seasons with Cleveland. The six-time All-Star demanded a trade following the 2016-17 season and was dealt to Boston. He hasn’t played in Cleveland since the 2017-18 opener.

Celtics center Al Horford (sore left knee) and forward Jayson Tatum (back contusion) could return Tuesday. Coach Brad Stevens said both were “questionable to probable” at the team’s shootaround.

Kris Humphries retires

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At one point, Kris Humphries was one of the NBA’s most-hated players. Because he married Kim Kardashian, I guess. I’m not sure his critics could articulate precisely why they loathed him.

Now, two years after last playing in the NBA, Humphries is retiring.

He announced his decision in The Players’ Tribune, also elaborating on his relationship with Kardashian:

Look, I should have known what I was getting into. I was definitely naive about how much my life was going to change. But the one thing that really bothers me is whenever people say that my marriage was fake.

There’s definitely a lot about that world that is not entirely real. But our actual relationship was 100% real. When it was clear that it wasn’t working … what can I say? It sucked. It’s never easy to go through the embarrassment of something like that — with your friends, with your family…. But when it plays out so publicly, in front of the world, it’s a whole other level. It was brutal.

I didn’t know how to handle it, because I never thought I was going to be famous in that way. I remember having this moment when I was getting booed so hard in Philly, and I thought to myself, “Why exactly are they booing me, though? Is it just because I’m That Guy from TV? Do they think I was trying to be famous? Is it because they think I disrespected the game of basketball?”

The last one killed me, because all I’ve ever wanted to be known for was basketball.

Humphries’ playing style was built for anonymity. He was a rebounding journeyman who spent 13 seasons with the Jazz, Raptors, Mavericks, Nets, Celtics, Wizards, Suns and Hawks.

But he had a knack for drawing attention.

As a kid, he swam faster than Michael Phelps. As he shifted attention to basketball, he tried to take on Michael Jordan’s persona (as detailed in his essay) and came across like a jerk. Then, he hooked up with Kardashian.

Their 72-day marriage will be the lasting memory of his career. It’s what exposed him to a far wider audience.

Maybe that’s not what he wanted, and he still had a successfully long NBA career. But that’s what he got.

D’Angelo Russell gets ball snatched from his hand in backcourt while not paying attention (video)

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D'Angelo Russell has had an excellent season. He became a first-time All-Star. He’s a Most Improved Player candidate. He put himself in line to earn a lot of money.

But this wasn’t his finest moment:

CJ Fogler:

The Nets lost to the Trail Blazers, who were boosted this Maurice Harkless steal (but suffered a much bigger loss in Jusuf Nurkic).