Home Unfiltered Articles Players Baseball Prospectus
Basketball Prospectus home
Click here to log in Click here for forgotten password Click here to subscribe

Click here for Important Basketball Prospectus Premium Information!

<< Previous Article
Premium Article Three Centers (04/17)
Next Article >>
Premium Article Starting Over (04/19)

April 18, 2012
Coach of the Year
Quantified

by Neil Paine

Printer-
friendly
Contact
Author

For better or for worse, the Coach of the Year race basically comes down to which team most exceeded the media's preseason expectations, which is usually synonymous with "the team whose record improved the most over last year".

Take last year, for instance. The Bulls won 75.6 percent of their games under Tom Thibodeau, a 25.6 percentage-point gain over their .500 record under Vinny Del Negro in 2010. That represented the biggest improvement made by any team in the NBA, and Thibodeau won Coach of the Year honors as a result. It's nothing new--the coach with the biggest year-over-year improvement also won in 2010 (Scott Brooks), 2007 (Sam Mitchell), and 2005 (Mike D'Antoni), with the award going to the league's second-biggest improvers in 2008 (Byron Scott) and 2009 (Mike Brown).

So it's pretty much established now that Coach of the Year = "Coach of the team who surprised us the most." In 2004, John Hollinger (writing for SI at the time) attempted to quantify this by looking at not just the team's record in the previous year, but also two years prior (with a regression-to-the-mean component included for good measure). Here's what John had to say:

"To determine how many games the coach was expected to win, I pieced together a simple formula: The team's winning percentage the previous season (two parts), the team's winning percentage from two seasons previous (one part), and a .500 season (one part). I included the .500 season to adjust for the fact that a coach with 60 wins every year for a decade would otherwise show up as "+0." Similarly, a coach who went 10-72 every year would have the same mark even though he was awful. Because the draft and the salary cap conspire to level the playing field, it's a necessary addition. Finally, one other caveat--I only used the coach's record from seasons where he coached at least 50 percent of the team's games.

Using this formula, we can evaluate over time how a coach has fared against the expectation. For example, [Larry] Brown won 54 games with the Pistons last season, after they had won 50 the previous two seasons. Based on the formula, he was expected to win 49 games, so he gets a +5 for winning 54. Summing those up over all 24 seasons of Brown's career, we find that he's +114, or about five games better than expected each season."

Trouble is, both the "compare to last year" method and Hollinger's set expectations using the team's performance in Year Y-1 (and Year Y-2) as a proxy for talent in Year Y. That's not always true, as the leaderboards for both systems will tell us this year:

"Look at Last Year" Method

Coach             Team     W     L     WPct     Y-1      +/-
-------------------------------------------------------------
Vinny Del Negro    LAC    38    23    0.623    0.390    0.233
Frank Vogel        IND    40    22    0.645    0.451    0.194
Rick Adelman       MIN    25    38    0.397    0.207    0.190
Byron Scott        CLE    20    40    0.333    0.232    0.102
Dwane Casey        TOR    22    40    0.355    0.268    0.087
Avery Johnson      NJN    22    40    0.355    0.293    0.062
Scott Skiles       MIL    29    31    0.483    0.427    0.057
Larry Drew         ATL    36    25    0.590    0.537    0.054
Scott Brooks       OKC    44    17    0.721    0.671    0.051
Keith Smart        SAC    18    36    0.333    0.293    0.041

Coach             Team     W     L     WPct     Y-1      +/-
-------------------------------------------------------------
Tyrone Corbin      UTA    32    30    0.516    0.476    0.041
Alvin Gentry       PHO    32    29    0.525    0.488    0.037
Lionel Hollins     MEM    36    25    0.590    0.561    0.029
Randy Wittman      WAS    13    31    0.295    0.280    0.015
Lawrence Frank     DET    23    38    0.377    0.366    0.011
Erik Spoelstra     MIA    43    17    0.717    0.707    0.009
Doug Collins       PHI    31    30    0.508    0.500    0.008
Kevin McHale       HOU    32    29    0.525    0.524    0.000
Tom Thibodeau      CHI    46    15    0.754    0.756   -0.002
Gregg Popovich     SAS    44    16    0.733    0.744   -0.011

Coach             Team     W     L     WPct     Y-1      +/-
-------------------------------------------------------------
Stan Van Gundy     ORL    36    25    0.590    0.634   -0.044
George Karl        DEN    34    27    0.557    0.610   -0.052
Mike Brown         LAL    39    23    0.629    0.695   -0.066
Mark Jackson       GSW    22    38    0.367    0.439   -0.072
Mike D'Antoni      NYK    18    24    0.429    0.512   -0.084
Doc Rivers         BOS    36    26    0.581    0.683   -0.102
Nate McMillan      POR    20    23    0.465    0.585   -0.120
Rick Carlisle      DAL    34    28    0.548    0.695   -0.147
Monty Williams     NOH    19    42    0.311    0.561   -0.250
Paul Silas         CHA     7    53    0.117    0.415   -0.298

Hollinger Method

Coach             Team     W     L     WPct     Y-1      Y-2     Exp %     +/-
-------------------------------------------------------------------------------
Vinny Del Negro    LAC    38    23    0.623    0.390    0.354    0.409    0.214
Frank Vogel        IND    40    22    0.645    0.451    0.390    0.448    0.197
Tom Thibodeau      CHI    46    15    0.754    0.756    0.500    0.628    0.126
Rick Adelman       MIN    25    38    0.397    0.207    0.183    0.274    0.122
Scott Brooks       OKC    44    17    0.721    0.671    0.610    0.613    0.109
Erik Spoelstra     MIA    43    17    0.717    0.707    0.573    0.622    0.095
Gregg Popovich     SAS    44    16    0.733    0.744    0.610    0.649    0.084
Lionel Hollins     MEM    36    25    0.590    0.561    0.488    0.527    0.063
Doug Collins       PHI    31    30    0.508    0.500    0.329    0.457    0.051
Avery Johnson      NJN    22    40    0.355    0.293    0.146    0.308    0.047

Coach             Team     W     L     WPct     Y-1      Y-2     Exp %     +/-
-------------------------------------------------------------------------------
Larry Drew         ATL    36    25    0.590    0.537    0.646    0.555    0.035
Kevin McHale       HOU    32    29    0.525    0.524    0.512    0.515    0.009
Scott Skiles       MIL    29    31    0.483    0.427    0.561    0.479    0.005
Tyrone Corbin      UTA    32    30    0.516    0.476    0.646    0.524   -0.008
Alvin Gentry       PHO    32    29    0.525    0.488    0.659    0.534   -0.009
Lawrence Frank     DET    23    38    0.377    0.366    0.329    0.390   -0.013
Keith Smart        SAC    18    36    0.333    0.293    0.305    0.348   -0.014
Mike Brown         LAL    39    23    0.629    0.695    0.695    0.646   -0.017
Dwane Casey        TOR    22    40    0.355    0.268    0.488    0.381   -0.026
Stan Van Gundy     ORL    36    25    0.590    0.634    0.720    0.622   -0.032

Coach             Team     W     L     WPct     Y-1      Y-2     Exp %     +/-
-------------------------------------------------------------------------------
George Karl        DEN    34    27    0.557    0.610    0.646    0.591   -0.034
Doc Rivers         BOS    36    26    0.581    0.683    0.610    0.619   -0.038
Mike D'Antoni      NYK    18    24    0.429    0.512    0.354    0.470   -0.041
Randy Wittman      WAS    13    31    0.295    0.280    0.317    0.345   -0.049
Mark Jackson       GSW    22    38    0.367    0.439    0.317    0.424   -0.057
Rick Carlisle      DAL    34    28    0.548    0.695    0.671    0.640   -0.092
Byron Scott        CLE    20    40    0.333    0.232    0.744    0.427   -0.093
Nate McMillan      POR    20    23    0.465    0.585    0.610    0.570   -0.105
Monty Williams     NOH    19    42    0.311    0.561    0.451    0.518   -0.207
Paul Silas         CHA     7    53    0.117    0.415    0.537    0.466   -0.350

That's right, Vinny Del Negro, who darn near got himself fired in March, would be your 2012 Coach of the Year by these tried-and-true methods of setting up coaching expectations.

Obviously, there has to be a better way of accounting for the raw talent on a team beyond simply using the franchise's previous W-L. And that's where Daniel Myers' Advanced Statistical Plus/Minus comes in. In essence, ASPM is a boxscore-based, more stable version of Regularized Plus/Minus that is probably the most predictive all-in-one advanced box-score stat out there right now. Denominated in efficiency differential, ASPM is ideal for projecting a team's performance via a minute-weighted average of the individual ratings of its players.

To set a team's expectations for 2012, I looked at each 2012 player's ASPM score from 2011 (using Daniel's latest spreadsheet). If a player played 500+ minutes in 2011, his projected ASPM for 2012 was his 2011 ASPM. If he played less than 500 minutes in 2011 (and isn't a 2012 rookie), he was given a constant -3.20 ASPM projection (the minute-weighted average of all low-minute non-rookies in 2011); if he is a 2012 rookie, he was given a constant ASPM of -1.54 (the minute-weighted average of all 2011 rookies). I then used these "projections" and each team's actual 2012 playing-time distribution to create an expected efficiency differential for the team in 2012.

Comparing the weighted average of their actual 2012 ASPMs to that expected differential, then, provides a measure of how much a team (and a coach) exceeded expectations, given the amount of talent on his roster. For instance, here are the expected and actual ASPMs for New Orleans in 2012:

Player              MP      Proj   Actual
-----------------------------------------
Marco Belinelli    1839    -1.69    -1.75
Greivis Vasquez    1545    -4.09    -0.43
Jarrett Jack       1530    -1.62     1.05
Chris Kaman        1372    -1.32    -1.64
Trevor Ariza       1350     0.05     0.78
Al-Farouq Aminu    1305    -3.04    -1.64
Gustavo Ayon       1004    -1.54     1.88
Carl Landry         889    -1.45    -1.14
Jason Smith         873    -2.54    -0.44
Emeka Okafor        781     1.14     0.03
Xavier Henry        694    -4.44    -2.93
Lance Thomas        495    -1.54    -2.81
Eric Gordon         234     1.36     2.13
DaJuan Summers      209    -3.20    -2.95
Solomon Jones       196    -3.09    -2.83
Squeaky Johnson     119    -1.54    -2.78
Chris Johnson        82    -3.20    -1.88
Trey Johnson         61    -3.20    -3.11
Jerome Dyson         56    -1.54    -4.69
Donald Sloan         41    -1.54    -5.61
Jeff Foote           39    -1.54    -6.54
-----------------------------------------
Team                       -9.32    -3.61
                                    +5.71

In fact, that +5.71 mark was the NBA's best. Given the talent of its players, New Orleans "should" have had a schedule-adjusted efficiency differential of -9.3, which, while not Charlotte-level bad, would have been well clear of Cleveland and Washington for the league's second-worst mark. Instead, the Hornets rank 23rd--still below-average, so not great by any means, but much better than you would have thought before the season if you looked at the players Monty Williams had to work with.

So by this metric, here is a truer ranking of the league's most excellent coaches:

Coach                   Tm      Proj   Actual   Diff
----------------------------------------------------
Monty Williams          NOH    -9.32   -3.61    5.71
Tyrone Corbin           UTA    -4.79    0.24    5.04
Larry Drew              ATL    -2.71    2.27    4.98
Gregg Popovich          SAS     1.85    6.62    4.77
Frank Vogel             IND    -0.72    3.06    3.77
Tom Thibodeau           CHI     4.78    7.85    3.07
Rick Adelman            MIN    -4.43   -1.70    2.74
Dwane Casey             TOR    -6.74   -4.06    2.67
Scott Brooks            OKC     4.20    6.87    2.67
Doug Collins            PHI     1.79    4.20    2.41
Kevin McHale            HOU    -1.61    0.74    2.35
George Karl             DEN     0.25    2.30    2.05
Alvin Gentry            PHO    -1.44    0.58    2.02
D'Antoni/Woodson        NYK     0.97    2.70    1.73
Rick Carlisle           DAL     0.38    1.85    1.47
Mark Jackson            GSW    -3.69   -3.06    0.64
Saunders/Wittman        WAS    -7.51   -7.00    0.51
Erik Spoelstra          MIA     6.41    6.86    0.45
Lionel Hollins          MEM     1.89    2.29    0.40
Byron Scott             CLE    -7.73   -7.45    0.28
Scott Skiles            MIL     0.27    0.24   -0.04
Lawrence Frank          DET    -5.31   -5.53   -0.22
Vinny Del Negro         LAC     3.84    3.16   -0.68
Westphal/Smart          SAC    -4.81   -5.79   -0.99
McMillan/Canales        POR     1.53    0.54   -1.00
Doc Rivers              BOS     3.56    2.11   -1.45
Avery Johnson           NJN    -3.82   -6.03   -2.21
Stan Van Gundy          ORL     4.25    1.53   -2.72
Mike Brown              LAL     5.99    2.31   -3.68
Paul Silas              CHA    -7.30  -14.28   -6.97

I think that's a fairer metric because it more accurately accounts for what a coach had to work with. And I suppose if you really want to make it more accurate, the "projections" could factor in a greater number of past years, and an aging adjustment could be added.

At any rate, a method like this represents a better way of assessing which coach truly squeezed the most out of his players. Perhaps Monty Williams doesn't deserve Coach of the Year on the basis of his team still being bad (just less bad than it could have been), and you might hold it against Corbin if the Jazz miss the playoffs, but it's tough to argue that Drew, Popovich, Vogel, and Thibodeau don't have their respective teams playing much better than we'd expect from how their players performed a year ago.

This free article is an example of the kind of content available to Basketball Prospectus Premium subscribers. See our Premium page for more details and to subscribe.

Neil Paine is an author of Basketball Prospectus. You can contact Neil by clicking here or click here to see Neil's other articles.

0 comments have been left for this article.

<< Previous Article
Premium Article Three Centers (04/17)
Next Article >>
Premium Article Starting Over (04/19)

RECENTLY AT BASKETBALL PROSPECTUS
State of Basketball Prospectus: A Brief Anno...
Tuesday Truths: March-at-Last Edition
Easy Bubble Solver: The Triumphant Return
Premium Article Bubbles of their Own Making: Villanova, Temp...
Tuesday Truths: Crunch Time Edition


MORE BY NEIL PAINE
2012-06-27 - Premium Article Making the Right Choice: NBA Drafts
2012-05-30 - Market Advantage: New York vs. L.A.
2012-05-21 - Most Dominant: Ranking the Champs
2012-04-18 - Coach of the Year: Quantified
2012-04-11 - Premium Article Early Entrants: The Guys Who Didn't Make It
2012-04-04 - Treadmill: Breaking the Cycle of Mediocrity
2012-03-30 - Premium Article UK vs. the NBA: Another Look
More...


Basketball Prospectus Home  |  Terms of Service  |  Privacy Policy  |  Contact Us
Copyright © 1996-2014 Prospectus Entertainment Ventures, LLC.