Saturday, June 07, 2008

Sharing the blame

David Berri, who authored the book Wages of Wins and writes the Wages of Wins Journal,
asked me the other day how well we could have expected the Tigers to perform this year given what the players did last year. He also wanted to know which players are underperforming and by how much. There is no definitive answer to these questions but one approach is Win Shares.

Bill James developed Win Shares as a way to estimate the number of wins a player contributes to a team based on his individual statistics. In the Win Shares approach, everything a player does (hitting, fielding, base running and pitching) is summarized with one number. Each win is worth three win Shares. For example, a player with 30 Win Shares is considered to have contributed 10 wins to his team.

The algorithm for determining Win Shares is much too complicated to be detailed here. If you want to learn more, you can read Win Shares written by Bill James and Jim Henzler and published by STATS, Inc. If you want a much briefer version, you can go to Baseball Graphs
The win shares algorithm has been critiqued and altered over the year and these changes are described at The Hardball Times.

I obtained the 2007 and 2008 Win shares statistics from The Hardball Times. THBT updates the win shares every couple of weeks and I thank Dave Studeman for running them the same day I told him I was hoping to use them in this article. Table 1 shows the win shares for batters in 2007 versus 2008. Basically, I calculated expected win shares for 2008 based on 2007 win shares and expected plate appearances in 2008. Using Miguel Cabrera as an example, here is how to read the table:

PA = 680 plate appearances in 2007
WS= 30 win shares in 2007

EPA= 700 expected plate appearances in 2008. This was done mostly to account for acquisitions made during the off-season. You would not, for example, expect Brandon Inge to have the same number of appearances in 2008 as a part-time player as he had in 2007 as a full-time player. Consequently, you would also not expect him to have as many win shares.

EWS=31 expected win shares in 2008 given 2007 win shares and EPA in 2008.

WS=6 win shares in 2008 as of June 5.

PWS= 17 projected win shares in 2008. This is calculated by simple extrapolation assuming Cabrera will perform the same way all season as he did through June 5.

WS diff= PWS-EWS

W diff= WS diff/3 because each win is worth 3 win shares.

Table 2 is similar to table 2 except it presents win shares for pitchers and uses innings pitched to determine expected win shares.



Table 1: Win Shares for Tigers batters - 2007 vs 2008



2007

2008

2008 - 2007

Player

PA

WS

EPA

EWS

WS

PWS

WS diff

W diff

Granderson

676

26

650

25

3

8

-17

-5.67

Jones

495

15

500

15

0

0

-15

-5.00

Cabrera

680

30

700

31

6

17

-14

-4.67

Ordonez

679

36

650

34

8

22

-12

-4.00

Sheffield

593

16

500

13

1

3

-10

-3.33

Renteria

543

18

600

20

4

11

-9

-3.00

Polanco

641

23

600

22

6

17

-5

-1.67

Raburn

148

5

150

5

0

0

-5

-1.67

Guillen

630

19

600

18

6

17

-1

-0.33

Rodriguez

515

13

450

11

4

11

0

0.00

Santiago

74

2

150

4

3

8

+4

+1.33

Inge

577

13

250

6

4

11

+5

+1.67

Thames

284

7

200

5

4

11

+6

+2.00

Others

----

----

200

4

3

8

+4

+1.33

Totals

----

----

6200

213

52

144

-69

-23



Table 2: Win Shares for Tigers pitchers - 2007 vs 2008


2007

2008

2008 - 2007

Player

IP

WS

EIP

EWS

WS

PWS

WS diff

W diff

Verlander

202

16

215

17

2

5

-12

-4.00

Willis

205

7

215

7

0

0

-7

-2.33

Zumaya

34

3

60

6

0

0

-6

-2.00

Robertson

178

8

185

8

1

3

-5

-1.67

Byrdak

45

4

50

4

0

0

-4

-1.33

Rodney

51

3

60

4

0

0

-4

-1.33

Seay

46

6

50

6

1

3

-3

-1.00

Miner

54

5

60

6

1

3

-3

-1.00

Jones

61

6

60

6

1

3

-3

-1.00

Grilli

80

4

60

3

1

3

0

0.00

Rogers

63

3

125

6

2

6

0

0.00

Bonderman

174

7

200

8

4

11

+3

+1.00

Galarraga

17

1

25

1

4

11

+10

+3.33

Lopez

9

0

25

0

4

11

+11

+3.67

Others

----

----

60

2

2

6

+4

+1.33

Totals

----

----

1450

84

23

65

-19

-6.33



Looking at the totals row in each table, we can see how many team win shares the Tigers would accumulate in 2007 if they performed the same way in 2008 as 2007. It comes out to 297 expected win shares in 2008 (213 for the batters and 84 for the pitchers). That is 99 expected wins assuming no injuries or player regression. So far this year, they have accumulated 75 win shares (52 and 23). Extrapolating that over 162 games, it comes to 209 win shares (144 for hitters and 65 for pitchers). That is equivalent to 70 wins.

So, if they keep up the same pace, the Tigers will lose 29 more games this year than expected based on their performance in 2007. Some of it is injuries to Curtis Granderson and Gary Sheffield and a few others but they haven't been hit that hard by injuries this year. So which players are underperforming the most?

Table 1 illustrates that six position players are underperforming by three or more wins over a full season.

Curtis Granderson (5.67 wins) - We can't blame Granderson for his hand injury but even if we lower his expected plate appearances to reflect time missed for the injury, it still comes to 4+ wins of underperformance.

Jacque Jones (5 wins) - Some people were not expecting much from him but he should have been expected to be a decent platoon player. Instead he had zero win shares at the time of his release.

Miguel Cabrera (-4.67) - He is tied for second on the team in win shares but he has simply underperformed. There is no excuse for him other than he is trying to adjust to a new league.

Magglio Ordonez (-4.00) - I'll excuse Ordonez for not repeating his career year of 2007. If I had used a three year average as the comparison rather than just last year, he would be performing just as expected. So, let's not blame Magglio.

Gary Sheffield (-3.33) - Sheffield has been hurt but he was hurt last year too so I wasn't expecting a full season of plate appearances from him. He has produced very little while playing though.

Edgar Renteria (-3.00) - Renteria had one of his best seasons last year but even if we take a three year average, he is still underperforming by more than 2 games.

On the pitching side, there are three players underperforming by 2 or more games:

Justin Verlander (-4.00) - He is apparently healthy and simply underperforming.

Dontrelle Willis (-2.33) - has been injured most of the season.

Joel Zumaya (-2.00) - has been injured all season.

My conclusion is that most of the team underperformance compared to 2007 is due to three things:

(1) the underperformance of the following players: Cabrera, Verlander, Granderson, J.Jones, Renteria and Sheffield.

(2) injuries to Zumaya, Granderson, Willis and Sheffield.

(3) Magglio Ordonez should not have been expected to repeat his amazing 2007 season.

So, for those who want to point the finger, there is plenty of blame to go around. For those who like to make excuses, there is some reason for that too. Regardless of how you look at it, it's been a very disappointing season for the Tigers.

4 comments:

  1. The win share stats were as interesting as they were puzzling. I'd expected Granderson to be one of the problems, given his injuries and recent slump. Though, maybe we should cut Verlander some slack. Outside of the two games where they've put up 10 plus, the Tiger offense is only giving him about 1.5 a game.

    ReplyDelete
  2. Verlander has been pretty good lately and has been very unlucky but remember that he had an ERA over 6.00 after 8 games. Also, his strikeouts are down and his walks are up. He hasn't been anything like the Verlander of last year but hopefully he is turning the corner now.

    ReplyDelete
  3. I love win shares and was thinking about doing a similar post, but you beat me too it and I'm glad you did. Nice work. Although, I'll disagree with you on Cabrera again, I really don't think all of his struggles can be chalked up to a new league, I just cannot buy that.

    ReplyDelete
  4. I didn't intend to suggest that his poor season was all due switching leagues. I just think that may be part of it. Statistically, the problem is he's not hitting as many line drives (the contact rate is the same). I don't really have a good explanation why that is the case.

    ReplyDelete

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