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. 

Hawks battle back to knot series with Wizards, 2-2

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Paul Millsap shoved Markieff Morris out of the way, grabbed an offensive rebound in the middle of the paint and pushed through a shot while Marcin Gortat bumped him to the floor.

The Wizards knocked down Atlanta. They didn’t stop the Hawks.

Millsap and Atlanta showed plenty of fight, topping Washington 111-101 in Game 4 Monday to tie their first-round series 2-2 after falling behind 2-0.

Have the Hawks seized meaningful momentum? History says no.

Teams that have won the first two games of a best-of-seven series at home then lost the next two on the road have won 81% of the time. The Wizards’ regular-season superiority still speaks loudly, and up to two more home games – starting with Game  5 Wednesday – also help.

Still, credit Atlanta for making the series competitive after digging such a big hole.

Millsap (19 points, nine rebounds, seven assists and two steals) soundly outplayed Markieff Morris (nine points on 3-of-10 shooting, -10) in the latest round of their personal feud. Millsap also got plenty of help with seven Hawks scoring double digits.

Kent Bazemore (16 points, seven assists and three steals) played meaningful defense and hit a couple big shots. Jose Calderon (10 points, five assists, +29 in 20 minutes) provided a huge spark. Dwight Howard (16 points and 15 rebounds) asserted himself for the first time this series. Taurean Prince (11 points on 5-of-7 shooting) picked his spots well. Dennis Schroder (18 points on 6-of-15 shooting) had his ups and downs. Tim Hardaway Jr. (15 points) at least offset some of his defensive shortcomings.

This was a total team win.

Washington, on the other hand, got little outside its starting backcourt. Bradley Beal (32 points) thrived, and John Wall (22 points and 10 assists) was still good in an off-by-his-standards performance. But the Wizards crumbled when either sat – especially with both on the bench in the late third/early fourth quarters. Erasing those few minutes with staggering would’ve helped, though it wouldn’t have been the answer tonight.

This has become a far less certain series than Washington hoped, but the Wizards don’t need a wild fix. They just need their top players to play better. Maybe going home will help.

Raptors break out best game of postseason, rout Bucks 118-93 to take 3-2 series lead

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Norman Powell was draining threes, throwing down dunks that would have won the contest All-Star weekend, and he finished with a career playoff-high 25 points on just 11 shots. Plus defensively he caused Khris Middleton trouble.

The Raptors finished with 28 assists, the most in a playoff game since Dwane Casey took over as coach.

Toronto shot 57.7 percent overall, a franchise playoff best.

The Raptors bench played well pitching in 27 points and growing the lead when they were in, part of an overall strong night from the role players in Toronto.

Combine that all with the expected good nights from Kyle Lowry and DeMar DeRozan and you get the Raptors best game of the playoffs. It looked like a different team than the one in Milwaukee.

Toronto raced out to an early lead and went on to rout the Bucks 118-93, giving the Raptors a 3-2 series lead.

This was a game where the Bucks tried to force the ball out of the hands of Lowry and DeRozan as much as they could, using their length and athleticism. However, Lowry had 10 assists, and DeRozan would get the ball off pindown screens and feel the double coming, move the ball, and another quick pass or two later the role-playing player Raptors were getting good looks and knocking them down. Or throwing it down like this.

Or this.

Toronto just looked more comfortable against the Bucks pressure, having seen it for so many games in a row, than they have all series.

Powell had 25 points for Toronto, Serge Ibaka had 19 and three blocks, Lowry had 16 points and 10 assists, DeRozan had 18 points and six assists, even DeMarre Carroll had 12 points on six shots.

The question for the young Bucks team is how does it bounce back from this kind of loss in the biggest NBA game most of them have ever played? Can they get their defensive edge back?

“We’re going to miss some shots, and we can’t let our offense dictate our defense,” Bucks coach Jason Kidd said postgame. “And also the turnovers, again. Right off the bat we had three…

“Our defense kind of got hit there in the first quarter, we knew that they were going to come after us, we had to expect that. And we just couldn’t respond.”

The Bucks had some runs in the second quarter and got the lead to nine at one point, but the Raptors always seemed to be in control.

Giannis Antetokounmpo had another strong game with 30 points on 12-of-19 shooting, and rookie Malcolm Brogdon pitched in 19 points on 11 shots, but for the most part the Bucks struggled with their offense in this game. As their coach noted — and as often happens to young teams — they let their offensive woes impact the other end of the court.

At home, the Bucks will likely feel more comfortable, and they will fight for their playoff lives.

The question is, can the Raptors be this sharp again and close them out? Or will the yo-yo nature of this team continue?

 

Kevin Durant will play in Game 4 for Warriors vs. Trail Blazers

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In case you were curious how serious Golden State was about closing out Portland in four…

After missing the last two games with a strained calf, both Warriors wins to put them up 3-0 in the series, the Warriors are bringing back Kevin Durant for Game 4.

Steve Kerr is also out tonight for Golden State, Mike Brown will coach the team.

There was buzz that Durant could have gone in Game 3 if needed, but the Warriors felt confident they would win without him and they don’t want this injury to linger. There’s no more holding him back now.

Durant averaged 25.1 points a game, and thanks to the space created by the other stars on the team had his most efficient season, with a true shooting percentage of 65.1. He also pulled down 8.3 rebounds a game, dished 4.9 assists, and had his best defensive season in a long time as well. If not for an injury after the All-Star break that had him missing games, he would have made a lot of voters’ All-NBA team.

He adds to Golden State’s size advantage against Portland. The Warriors would like to close out the series tonight and get additional rest before facing the Clippers or Jazz in the next round.

Serge Ibaka is dunking and Giannis Antetokounmpo isn’t going to stop him. Twice. (VIDEO)

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The Toronto Raptors had their best half of their first-round series against the Bucks, taking an early lead and, despite a little shooting slump midway through the second they were up nine at the half.

That was all topped off by two emphatic Serge Ibaka dunks. Ones Giannis Antetokounmpo wasn’t going to stop.

Ibaka dunked around him more than over the Greek Freak, but still.