Do Coaches Matter?

Jeff Gross

Yesterday, Citizen saxmanager posted a Fanshot (yes, they still exist) linking to a Yahoo! article written by a newer writer named Justin Haskins. He's mainly a political writer, but his analysis of the Clipper situation brought up an interesting topic and got me thinking.

In a nutshell, he proposed that given the choice between trading Jordan, Bledsoe, and Butler for Kevin Garnett and Paul Pierce, and trading two picks (2015 first and second rounders) for Doc Rivers, did the Clippers make the right choice in choosing to go with Rivers? He concedes that if Chris Paul wanted Rivers, the choice was very easy, but that the Clippers (and Paul) may have regrets later on, overrating the Doc-Rivers-effect.

But while this writer seems to think the Clippers overvalue the effect of coaches, I think Haskins is undervluing them. He gives a number of examples, including Rivers, Vinny Del Negro, and Larry Brown, demonstrating that coaches with good teams have good records, and coaches with bad teams have bad records. That seems to make sense, but what I think he's completely ignoring are the coaches with good teams that have bad records, and vice versa.

What is a Good Coach?

To me, a good coach is one that takes talent and performs better than expected, and a bad coach is one that takes talent and underperforms. Using ESPN's stat, Expected Wins, basically relies on point differential and correlates well with actual standings, the Clippers under Vinny Del Negro should have had 61 wins but ended with 56. Considering the fact that they had one of the best clutch players in the league in Chris Paul, you'd really expect them to overperform (as point differential doesn't really account for the ability to win tight games). Underperforming by 5 wins seems like the mark of a bad coach, doesn't it? And it was actually the 4th worst underperformance in the league.

But before we get ahead of ourselves and start Vinny-bashing, this really isn't enough to answer the question, is it? This is just one season, and one example, and could be explained by any number of reasons. What we need are more examples and more seasons before we can determine if we can actually identify "good" coaches and whether Doc Rivers is one of them, thus making the trade worthwhile.

What are Expected Wins?

First, I'll explain what Expected Wins are. Expected Wins is a formula used by ESPN's former analyst John Hollinger, and it's based on the Pythagorean Expectation created by Bill James for baseball. Noted statisticians Daryl Morey (also Houston's GM) and Dean Oliver use similar methods. All of these methods revolve around points scored and points allowed, and generally correlate very well to actual wins.

The inherent flaw with using Expected Wins (or any point differential measure) is that blowouts tend to skew the extremes ends of the spectrum. That is, one 20-point victory can offset 20 one-point losses. This makes strong teams that can score a lot look like they are underperforming, and weak defensive teams look like they are overperforming.

So when we look at the 2012-13 season to see if there were any other interesting things to discover, as expected, we see some surprising teams at the top and the bottom of the pack. Three of the top offensive teams, the Thunder, Clippers, and Spurs are huge underperformers, and two of the bottom defensive teams, the Bobcats and Suns are huge overperformers. So maybe if we can pick out some of these abnormalities, say by adjusting for the number of blowouts, it will normalize the Expected Wins a bit.

There are better ways to do this, but I figured the easiest way would be to take the "bite" out of any blowouts. For the purposes of this exercise, any victory (or loss) greater than 15 points will be considered a blowout. And so in order to lessen the effect, I will decrease any blowout to a 15 point victory (or loss). No team can win by more than 15, or lose by more than 15. And I think this will provide a more level basis on which to evaluate the different coaches.

2013

ACTUAL RECORD

EXPECTED RECORD

ADJUSTED EXPECTATION

Change

RK

TEAM

W

L

W

L

W

L

1

Miami

66

16

65

17

61

21

-5

2

Golden State

47

35

44

38

44

38

-3

3

Brooklyn

49

33

47

35

46

36

-3

4

Chicago

45

37

42

40

42

40

-3

5

Denver

57

25

57

25

54

28

-3

6

San Antonio

58

24

61

21

55

27

-3

7

Milwaukee

38

44

36

46

36

46

-2

8

LA Lakers

45

37

45

37

43

39

-2

9

Boston

41

40

40

41

39

42

-2

10

Atlanta

44

38

42

40

43

39

-1

11

Memphis

56

26

56

26

55

27

-1

12

Philadelphia

34

48

29

53

33

49

-1

13

Utah

43

39

41

41

42

40

-1

14

New York

54

28

55

27

53

29

-1

15

Charlotte

21

61

14

68

20

62

-1

16

Portland

33

49

30

52

33

49

0

17

Dallas

41

41

39

43

41

41

0

18

Sacramento

28

54

26

56

28

54

0

19

Phoenix

25

57

21

61

26

56

1

20

LA Clippers

56

26

61

21

57

25

1

21

Oklahoma City

60

22

67

15

61

21

1

22

Toronto

34

48

36

46

36

46

2

23

Indiana

49

32

54

27

51

30

2

24

Detroit

29

53

28

54

31

51

2

25

Minnesota

31

51

33

49

33

49

2

26

New Orleans

27

55

28

54

29

53

2

27

Houston

45

37

52

30

48

34

3

28

Cleveland

24

58

26

56

28

54

4

29

Orlando

20

62

19

63

24

58

4

30

Washington

29

53

32

50

34

48

5


Getting rid of some of the blowout effect, it appears to have corrected much of the problem. Bad teams like Phoenix and Charlotte performed mostly as expected, and good teams like the Clippers and Thunder were exactly what their point differential indicated: good teams.

Who are the Good Coaches?

So now we can get back to our original issue: Who are the good coaches? Or more specifically, which coaches are getting better execution out of their players, winning tight games and properly utilizing the talent?

It's not just a matter of where the teams fall on this list, but rather where they fall on this list given the talent on the roster. The Clippers and Thunder have Chris Paul and Kevin Durant respectively, and yet they've failed to win enough close games to overachieve beyond their point differential. Both teams are sub-.400 in games decided by 3 points or less. That's absurd. Miami and Golden State, on the other hand, have great records in close games (both above .600), and they have successfully overachieved beyond their point differential. They, too, have stars capable of getting clutch buckets in LeBron James and Stephen Curry, and yet it appears that their coaches (or assistant coaches coughGoldenStatecough) have been able to get their teams to execute down the stretch to win these close games. And it's really not at all surprising to see well-known coaches such as Gregg Popovich and Tom Thibodeau overachieving.

Unfortunately, determining who the good coaches are cannot be done based on one year's evidence. We see some signs of evidence of teams overachieving/underachieving with respect to point differential, but it can't really be quantified how much of that is due to the coach. This is where historical data comes into play. For now, given that these take a lot of time to throw together, I'll just go back 2 more years, to 2010-11, the beginning of the Vinny Del Negro era.

2012

ACTUAL RECORD

EXPECTED RECORD

ADJUSTED EXPECTATION

Change

RK

TEAM

W

L

W

L

W

L

1

LA Lakers

41

25

37

29

35

31

-6

2

Memphis

41

25

39

27

38

28

-3

3

San Antonio

50

16

51

15

47

19

-3

4

Detroit

25

41

20

46

22

44

-3

5

Utah

36

30

35

31

34

32

-2

6

Brooklyn

22

44

17

49

20

46

-2

7

Chicago

50

16

54

12

48

18

-2

8

Indiana

42

24

42

24

40

26

-2

9

Atlanta

40

26

43

23

39

27

-1

10

Houston

34

32

34

32

33

33

-1

11

Miami

46

20

49

17

45

21

-1

12

Cleveland

21

45

15

51

20

46

-1

13

Oklahoma City

47

19

48

18

46

20

-1

14

Dallas

36

30

36

30

35

31

-1

15

Denver

38

28

41

25

37

29

-1

16

Phoenix

33

33

32

34

33

33

0

17

Boston

39

27

40

26

39

27

0

18

LA Clippers

40

26

40

26

40

26

0

19

Orlando

37

29

35

31

37

29

0

20

Sacramento

22

44

19

47

22

44

0

21

New York

36

30

42

24

37

29

1

22

Washington

20

46

20

46

22

44

2

23

Milwaukee

31

35

34

32

33

33

2

24

New Orleans

21

45

22

44

23

43

2

25

Minnesota

26

40

27

39

29

37

3

26

Toronto

23

43

24

42

26

40

3

27

Portland

28

38

31

35

32

34

4

28

Golden State

23

43

24

42

27

39

4

29

Charlotte

7

59

5

61

11

55

4

30

Philadelphia

35

31

45

21

42

24

7

2011

ACTUAL RECORD

EXPECTED RECORD

ADJUSTED EXPECTATION

Change

RK

TEAM

W

L

W

L

W

L

1

San Antonio

61

21

59

23

57

25

-4

2

Oklahoma City

55

27

53

29

51

31

-4

3

Dallas

57

25

55

27

54

28

-3

4

Charlotte

34

48

27

55

31

51

-3

5

Portland

48

34

46

36

45

37

-3

6

New Orleans

46

36

44

38

43

39

-3

7

Utah

39

43

35

47

37

45

-2

8

Chicago

62

20

64

18

60

22

-2

9

Atlanta

44

38

38

44

42

40

-2

10

LA Lakers

57

25

60

22

56

26

-1

11

Boston

56

26

59

23

55

27

-1

12

Golden State

36

46

34

48

36

46

0

13

Washington

23

59

19

63

23

59

0

14

Indiana

37

45

37

45

37

45

0

15

LA Clippers

32

50

31

51

32

50

0

16

Brooklyn

24

58

21

61

24

58

0

17

Phoenix

40

42

38

44

40

42

0

18

Memphis

46

36

49

33

47

35

1

19

New York

42

40

43

39

43

39

1

20

Cleveland

19

63

15

67

20

62

1

21

Detroit

30

52

29

53

31

51

1

22

Denver

50

32

56

26

51

31

1

23

Miami

58

24

64

18

60

22

2

24

Milwaukee

35

47

38

44

37

45

2

25

Orlando

52

30

59

23

55

27

3

26

Houston

43

39

48

34

46

36

3

27

Toronto

22

60

2

60

25

57

3

28

Sacramento

24

58

24

58

27

55

3

29

Philadelphia

41

41

46

36

45

37

4

30

Minnesota

17

65

21

61

24

58

7


Well, it looks like Vinny's at least been consistently solid. We all knew he wasn't a bad coach, but he doesn't seem to be doing what Popovich is doing, where he always has his team outperforming their point differential without relying on blowouts to do so. Thibodeau seems to always be in the top echelon as well. Of course, "top echelon" just means getting your team a couple extra wins, and a couple wins based on point differential is really the difference between a couple buzzer beaters falling or not. It's not really an exact science. That said, a couple wins are also the difference between going to the finals and getting bounced in the first round, so perhaps it's at least worth looking at.

Conclusion

So have we successfully addressed the issue of whether coaching matters? Can we even identify good coaches? There's really no perfect way to measure the asset that is a coach. It's almost intangible, and yet we know it exists. Well, we think we know it exists. We see terrible substitution patterns, and we see botched possessions out of time-outs. And the grass always looks greener on the other side, doesn't it? But I'm sure even the great Gregg Popovich frustrated fans when he insisted on playing an ice cold Manu Ginobili during the playoffs, or decided to completely freeze out the always-productive DeJuan Blair.

Can we ever truly know if Justin Haskins is right, and that the Clippers should have traded for Garnett/Pierce rather than for Rivers/Redick/Dudley? No. Not really, but they are very different options. The Rivers/Redick/Dudley move looks to the future much more than a Garnett/Pierce move, and with 5 years of Paul/Griffin, there will be more opportunities down the line, and Redick/Dudley will be needed.

Can we determine if the Clippers are overrating their coach? Again, not really. But my analysis at least shows that for the last 3 years, Rivers has always gotten his teams to at least play to their potential or exceed it, which is never a bad thing. We must also remember that the alternatives were Lionel Hollins, Brian Shaw, Byron Scott, and Alvin Gentry, the last of whom is now an assistant coach. Could the Clippers have gotten Gentry to be an assistant coach to a head coach other than Rivers? Maybe not, and that's an opportunity cost worth considering as well.

I honestly don't think the Clippers will ever regret their moves this summer. They made a bold choice, and other than a few media outlets here and there, a universally-praised one. Rivers had the reputation as being the best coach on the market, and they got him. One day, maybe we will come up with a better way to rate coaches, and perhaps then we will be able to determine if our coach is overrated. For now, all we can do is set high expectations, and hope that Rivers and the rest of the Clippers can meet them.

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