Thursday, July 21, 2011

Why Mark Jackson (and every other coach) Doesn't Matter

Over at the Wages of Wins Journal (one of my favorite NBA blogs), there is a raging debate on the value of coaches. The general premise of Arturo Galletti’s post is that coaches in the NBA only matter in one regard: allocating playing time. Every other facet, like when you hear that a coach is making the team “tougher”, or is a “players coach”, doesn’t mean a thing. Their only value is determining which players see the floor, and which ride the pine.

I also believe that coaches add very little value to a team. Time after time it is shown that best way to predict how a team will perform is to look at the past statistics of the players: they are a much better indicator of a team’s strength then anything having to do with the coach. I want to take Arturo’s point a little bit farther though. In arguing that a coach’s main impact is allocating minutes, he implies that the allocation of minutes is an important consideration in whether a team wins or not. I know this sounds ludicrous, but I am suggesting that allocating minutes properly to the best players on the team, while important, doesn’t matter too much.

The above chart is simply a graph of two columns of data found in Arturo’s post: the percentage of minutes coaches properly allocated, and the total of a team’s wins produced. You would think that there would be a high correlation between these two numbers: teams that gave minutes to their best players would tend to do better than teams that did not. As it turns out, this correlation isn’t too strong, with an r2 of only 0.39. This means that, roughly speaking, 39% of the total of a team’s wins produced is due to the proper allocation of minutes. That is strong evidence to suggest that minute allocation matters, but equally strong evidence that it doesn’t matter too much. Even if Toronto Raptors coach Jay Triano had allocated his players minutes efficiently last year (instead, he only allocated 3% of his player’s minutes properly, no wonder he got fired), they would still have sucked. The fact is, better minute allocation can’t make up for bad players.


  1. Interesting assertion, and well argued. But I want to draw your attention to the chart Arturo included in his article, which assessed Minutes Per Game Correlation to Wins Produced per 48 Minutes and Wins produced. The top 15 teams only had three non-playoff clubs: Milwaukee, Golden State, Utah and Sacramento. The bottom 15 had only two playoff clubs: Orlando and Denver.

    What sticks out to me here is that the non-playoff teams had coaches who properly allocated minutes to the best players also were lauded for also keeping teams upbeat in the face of turmoil. No one questioned that players enjoyed playing for Keith Smart. Sloan's and D-Will's departures were catastrophic for the Jazz, but Ty Corbin had the respect of his players. Skiles I admittedly know little about, but I think his job is safe in Milwaukee, and he had a pretty roster (offensively at least). His players chafe at his style eventually, but that hasn't happened yet.

    Meanwhile, Orlando and Denver are interesting cases in the bottom half. Orlando had chemistry issues all year, with the midseason trade that brought overpaid, underachieving players to the team, as well as rising talk about Dwight Howard's impending free agency. Denver's inclusion must be, at least in part, related to when Melo and Billups were both on the team. Anyone who watched Denver after the trade deadline knows that it was George Karl's coaching that made that team successful, and most of that coaching was done in the locker room, managing personalities, as well as minutes. The bottom of the list is full of teams that were rife with chemistry issues the entire year.

    So, while you and Arturo I think are onto something, both of your are perhaps undervaluing the importance of chemistry and personality management. I'm not sure how that can be charted, however.

  2. First, a mea cupla: my college statistics professor would be horrified if I didn't state what R-Squared means more clearly. Really what I meant to say above is that "39% of the variation in Team Wins Produced is explained by Proper Minute Allocation." A subtle, but important distinction.

    I did a similar exercise to both the top 15 teams in minute allocation, and the bottom 15 teams in minute allocation. In both cases, and I acknowledge that the smaller sample size probably has something to do with it, the R-Squared value got lower, 0.21 for the top 15 teams, and 0.25 for the bottom 15 teams.

    I suspect Arturo will address some of your questions in the promised part 2, but I'll leave you with this: look at the best team at minute allocation, the Philadelphia 76ers. Doug Collins did a phenomenal job of allocating minutes: it's pretty damn hard to do better than 85%. The 76ers, however, still finished 41-41 and got bounced from the playoffs in four games. Ultimately, it is the quality of players that matters, with a small role being played by coach.

  3. Let's see what part 2 says. Meanwhile, Jorge Sierra disagrees with my assertions about Milwaukee's chemistry: