David Berri on Adjusted Plus/Minus

1 Comment

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. 

Tyronn Lue says he plans to keep minutes down for LeBron, Love, Irving

CLEVELAND, OH - JUNE 10:  Head coach Tyronn Lue of the Cleveland Cavaliers talks to LeBron James #23 of the Cleveland Cavaliers against the Golden State Warriors in Game 4 of the 2016 NBA Finals at Quicken Loans Arena on June 10, 2016 in Cleveland, Ohio. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, User is consenting to the terms and conditions of the Getty Images License Agreement.  (Photo by Jason Miller/Getty Images)
Getty Images
1 Comment

There have been studies that have shown this, or you can just take the Gregg Popovich eye test, but we know this:

Rested players perform better and are less likely to be injured.

Which is why the trend toward resting players in the NBA is not going away. Enter Cavaliers coach Tyronn Lue, via Cleveland play-by-play man Fred McLeod.

LeBron James may not like it, but this is the right move by Lue, both in terms of trying to repeat and for future years. The Cavaliers are going to need a healthy LeBron, Kyrie Irving, and Kevin Love if they are going to pass the test the Warriors present again.

The league schedulers have done an impressive job of reducing the four-games-in-five-nights on the road and back-to-backs. However, as long as the NBA plays 82 games, fatigue and rest will be issues — and we know the owners and players are not giving up the revenue to go to a more reasonable 60-game schedule. Which means what you get now is the new reality.

How Big Papi helped save Al Horford’s wedding day

BOSTON, MA - JULY 08:  Al Horford of the Boston Celtics, holding his son Ean, hugs David Ortiz #34 of the Boston Red Sox after throwing out the first pitch before the game between the Boston Red Sox and the Tampa Bay Rays at Fenway Park on July 8, 2016 in Boston, Massachusetts.  (Photo by Maddie Meyer/Getty Images)
Getty Images
Leave a comment

Al Horford is big in his native Dominican Republic.

But he’s no David Ortiz.

The Red Sox throwback slugger is THE MAN in the Dominican — and when Horford needed to get something big done at the last minute on his wedding day, he reached out to Ortiz. Who was the fixer.

As told to Andrew Sharp at Sports Illustrated, Horford was getting married on Christmas Eve in the Dominican, and he needed assistance.

“We’re down there, and I realize I’m supposed to get a limo for [my wife], to pick her up and take her to where we’re getting married,” Horford says. “And then, obviously being in the Dominican Republic, things never go how they’re supposed to. So three hours before the wedding, we find out that there’s no limo….

Eventually he did what one does in the case of Dominican emergencies. He called David Ortiz: “I’m like, ‘Hey man, this is what’s going on. We’re getting married in a couple hours. I need a car. What am I going to do?’ ”

“Don’t worry,” Ortiz said. “I got you.”

Ortiz wasn’t even on the island at this point, but it didn’t matter. He told Horford to send a friend over to Ortiz’s house to pick up his Rolls-Royce Phantom. “I’ll have it there in 30 minutes,” Ortiz said. “I just gotta get it washed.”

Horford was amazed. “He didn’t even know my guy down there,” he laughs. “I sent a friend of mine. And he picks up the Phantom, brings it over to my wife. . . . And you know, that’s a very expensive car. But [Ortiz] tells me to keep it until I leave. So we’re there for a couple more days, and we have the car the whole time. It’s just one of those things, it shows he has a really big heart.”

Ortiz is going to be missed in Boston.

Horford is going to fit in brilliantly — on and off the court.

Heat’s Josh McRoberts says he broke foot in Game 6 vs. Raptors, remains out

MIAMI, FL - SEPTEMBER 26: A portrait of Josh McRoberts #4 of the Miami Heat on September 26, 2016 in Miami, Florida. (Photo by Rob Foldy/Getty Images)
Getty Images
2 Comments

To call Josh McRoberts‘ time in Miami injury plagued might be the understatement of the decade.

Now with Chris Bosh out, the Heat could really use McRoberts at the four, but “shockingly” he is not healthy. Wednesday he finally admitted the reason he has been limited in training camp with foot issues.

McRoberts run of bad luck continues. And foot injuries — when your job involves running up and down a hardwood floor — are something that has to be taken seriously and allowed to fully heal, lest they become chronic. I’m not sure the Heat can bet on a lot out of McRoberts this season.

With no Bosh and McRoberts, expect Derrick Williams, Udonis Haslem, and maybe Luke Babbitt will get some run there. Coach Erik Spoelstra also likely will have some small lineups where Justise Winslow will play the four.

51Q: Will Larry Bird’s renovation of the Pacers pay off?

Larry Bird, Paul George
AP Photo/Michael Conroy
1 Comment

We continue PBT’s 2016-17 NBA preview series, 51 Questions. For the past few weeks, and through the start of the NBA season, we tackle 51 questions we cannot wait to see answered during the upcoming NBA season. We will delve into one almost every day between now and the start of the season.

There are two types of basketball analysts: Those who believe the Pacers improved by swapping George Hill for Jeff Teague and those who believe Indiana got worse in the trade.

Teague uses his superior quickness in the pick-and-roll to score and assist more. Hill defends better, commits fewer turnovers and shoots more efficiently.

I prefer Hill. Larry Bird opted for Teague.

I can’t wait to see who’s right.

Though I’m inclined to value Hill’s less-flashy contributions – and like his lead-guard skills if he were called upon for that role – I’m also not arrogant enough to believe I certainly know better than Bird. An all-time great who has excelled as a player, coach and executive deserves some benefit of the doubt.

Bird is leveraging it now.

Seemingly unsatisfied with the team that reached consecutive conference finals in 2013 and 2014, Bird has now fully torn down the roster to build a more dynamic offense around Paul George. The Pacers president has long talked about the change, and we’ll learn this season whether his vision will bear fruit.

In addition to trading Hill for Teague, Bird let Lance Stephenson leave in free agency, deemphasized and traded Roy Hibbert, offended David West into leaving and fired Frank Vogel. In came Monta Ellis, Rodney Stuckey, Myles Turner, Thaddeus Young, Teague and Nate McMillian.

And Bird hasn’t stopped after jettisoning everyone who regularly started with George in those conference-finals runs. Indiana will miss Ian Mahinmi‘s defense – maybe more than Al Jefferson works as a change-of-pace in the low post. But Bird is fully embracing the course of trading defense for offense.

Debate how he addressed it, but the team’s identity was clear. In the last four years, the Pacers stunk offensively and thrived defensively. Their rank in points per possession:

  • Offense: 20th, 23rd, 23rd, 25th
  • Defense: 1st, 1st, 7th, 3rd

The beauty is in the eye of the beholder. I see an excellent defense propping up an offense that could have been better. Bird saw a struggling offense and couldn’t look past it.

Indiana now has a deep squad of players who can break down opponents off the dribble. They will have matchup advantages – if they pass well enough to find the player in favorable position. The ball will move plenty between the hardwood and the dribbler’s hands. Between players? That’s a major question mark.

It’s one of numerous hitches in Bird’s plan.

He tried to fast-track the offense last year by moving George from small forward to power forward. Despite Bird’s demands, George resisted. The plan was largely scrapped early in the season.

McMillian was also a curious choice given Bird’s stated goals. McMillian’s Trail Blazers and SuperSonics teams usually played slow. Still, perhaps the coach can adapt his scheme to fit his players (and appease his boss). Bird chose McMillian for a reason, after all.

Bird chose it all.

This is the team he long desired – for better or worse.