When a 42 yearold pitcher has a 1.87 ERA in 211 innings pitched, you can’t help wondering if he did something unusual for his age. This is a great season for someone in their prime. But how to measure this? I tried a couple of different ways.
First, I looked at every pitcher’s RSAA with 150 or more
innings pitched from 19202005. RSAA is a stat Lee Sinins uses in his “Complete
Baseball Encyclopedia.” It is “Runs saved against average. It's the amount of
runs that a pitcher saved vs. what an average pitcher would have allowed.” It
can be negative and is park adjusted. To adjust RSAA for age, I multiplied each
of these pitcher’s RSAA times the absolute value of their age minus the typical
peak age. To get peak age, I found the average age for the 250 best RSAA
seasons from 19202005. It was 28.93. So the farther away from the peak age a
pitcher was, the bigger bonus he got. Of course, the farther away from the peak
age a pitcher gets, the less likely he is to have a high RSAA (I did not
include pre1920 or dead ball era seasons since there were so few HRs hit then,
making the pitching environment much different).
Pitcher

YEAR

RSAA

AGE

Age Points

Roger
Clemens

2005

53

42

692.77

Dazzy
Vance

1930

64

39

644.55

Randy
Johnson

2002

62

38

562.41

Grover
C Alexander

1927

50

40

553.56

Randy
Johnson

2004

50

40

553.56

Lefty
Grove

1939

54

39

543.84

Dwight
Gooden

1985

58

20

517.87

Lefty
Grove

1936

70

36

494.98

Randy
Johnson

2001

59

37

476.20

Phil
Niekro

1978

46

39

463.27

Clemens had an RSAA of 53 in 2005. His age minus 28.93 is
13.07. That times 53 is 692.71 “age points (the difference is due to rounding).
So by this measure, yes, Clemens had the best age adjusted season. Notice that
there is a “young” pitcher here, Dwight Gooden from 1985. He had a great year
but was not close to the peak age. So he had one of the best age adjusted
seasons.
But by how much did Clemens exceed the expected RSAA for a
42 yearold pitcher? We can’t simply see how much each guy exceed the average
RSAA for each age because its possible that a pitcher must be pretty good to be
used at very young and very old ages. Table 2 shows the average RSAA for all
pitchers with 150 or IP from 19202005 by age.
AGE

RSAA

19

8.60

20

10.89

21

3.75

22

3.47

23

4.83

24

5.70

25

5.83

26

6.59

27

5.48

28

5.47

29

6.51

30

6.82

31

6.36

32

5.96

33

7.26

34

7.32

35

8.64

36

8.92

37

8.52

38

7.64

39

10.33

40

11.25

41

3.44

42

6.25

43

0.67

44

4.29

45

2.20

46

5.00

47

4.00

Notice that the RSAA is much higher for ages 39 and 40 than
for ages 2730. There were only 40 pitchers aged 39 while there were 123 at age
27. So the old pitchers are not necessarily as good as the young pitchers or
there would be more “old” pitchers. It seems only the good ones are allowed to
keep pitching at an advanced age. To get an idea of a truer aging pattern, I
looked only at pitchers who had at least 10 seasons with 150+ IP. I wanted to
only include “good” pitchers since you have to be good to pitch this long. This
helps reduce the problem illustrated by Table 2 and allows us to see how
performance changes with age. The graph below shows this pattern.
The graph shows the average RSAA for each age from 19 to 47
for pitchers who had at least 10 seasons with 150+ IP. Notice the equation y = 0.0556x^{2}
+ 3.1648x  30.949. It tells us the mathematical relationship between age and
RSAA with y being RSAA and x being age. The R^{2} says that 85.42% of
the variation in RSAA is explained by age. This equation is a second order
polynomial
Since this only applies to the select group of “good”
pitchers who had at least 10 seasons with 150+ IP, I had to make an adjustment
to apply it to all pitchers. All pitchers in this group had an average RSAA of
6.23 while the “good” pitchers had 12.28. The difference is 6.05. To apply the
equation to all pitchers, I reduced the intercept (30.949) in the equation by
6.05. So it became about –37. To predict any pitcher’s expected RSAA based on
age, I used the equation
RSAA = 0.0556*AGE^{2} + 3.1648*AGE – 37
This allows all pitchers to have a realistic aging pattern
and it is adjusted downward to reflect the lower quality of all pitchers as
opposed to the “good” pitchers who had at least 10 seasons with 150+ IP. Each
pitcher had their RSAA predicted based on their age and this equation. Then
their predicted RSAA was subtracted from their actual RSAA. The more they
exceeded their predicted RSAA, the better their “age adjusted” performance.
Table 3 below shows the top 20 seasons.
Pitcher

YEAR

AGE

RSAA

Pred

Diff

Pedro
Martinez

2000

28

77

8.03

68.98

Lefty
Grove

1932

32

75

7.34

67.66

Lefty
Grove

1931

31

75

7.68

67.32

Lefty
Grove

1936

36

70

4.88

65.12

Pedro
Martinez

1999

27

71

7.92

63.08

Roger
Clemens

1997

34

69

6.33

62.67

Dazzy
Vance

1930

39

64

1.86

62.14

Lefty
Gomez

1937

28

69

8.03

60.98

Red
Faber

1921

32

68

7.34

60.66

Lefty
Grove

1935

35

65

5.66

59.34

Dizzy
Dean

1934

24

66

6.93

59.07

Randy
Johnson

2002

38

62

2.98

59.02

Dolf
Luque

1923

32

66

7.34

58.66

Pedro
Martinez

1997

25

65

7.37

57.63

Lefty
Grove

1930

30

64

7.91

56.10

Greg
Maddux

1995

29

64

8.02

55.98

Roger
Clemens

2005

42

53

2.16

55.16

Randy
Johnson

2001

37

59

3.98

55.02

Frank
Sullivan

1955

25

62

7.37

54.63

Randy
Johnson

1999

35

60

5.66

54.34

Clemens 2005 does well, at 17^{th }(out of 6,690
pitchers). But it was not the best age adjusted year ever. If you plug in 28
into the equation, you get 8.03. That is the expected RSAA for a 28 yearold
pitcher. But since Pedro Martinez actually had an RSAA of 77, he exceeded his
prediction by 68.98. No other pitcher beat the trend by more. Some of the
pitchers are old by baseball standards, but not all of them.
One aspect of RSAA is that the fielders will have a role.
The better the fielders behind the pitcher, the higher the RSAA. Next week I
will do the same analysis but with a defense or fielding independent measure of
pitching. This will isolate the age adjusted performance solely due to the
pitcher.
Here is a response to one of the comments
Anyone close to the average peak age has no chance. My rationale was to try to reward both being good and far away from the peak age. I agree that method 1 is not perfect. So that is why I did method 2. Notice there that the best guy is Pedro Martinez at age 28, close to the peak age.
Yes, I could square the age difference. Here are the top 20 from the pitchers with 150+ IP from 19202005
Pitcher YEAR AGE RSAA pts
Roger Clemens 2005 42 53 9053.7197
Dazzy Vance 1930 39 64 6489.9136
Jack Quinn 1928 44 27 6131.8323
Randy Johnson 2004 40 50 6127.245
GrovC Alexander 1927 40 50 6127.245
Lefty Grove 1939 39 54 5475.8646
Randy Johnson 2002 38 62 5100.4238
Nolan Ryan 1991 44 21 4769.2029
Phil Niekro 1978 39 46 4664.6254
Roger Clemens 2004 41 32 4661.9168
Dwight Gooden 1985 20 58 4625.2042
Ted Lyons 1942 41 30 4370.547
Bob Feller 1939 20 51 4066.9899
Jack Quinn 1926 42 23 3928.9727
Phil Niekro 1984 45 15 3873.6735
Randy Johnson 2001 37 59 3842.3691
Phil Niekro 1979 40 30 3676.347
Jack Quinn 1924 40 30 3676.347
Don Drysdale 1957 20 45 3588.5205
Nolan Ryan 1989 42 21 3587.3229
Here is a response to one of the comments
Anyone close to the average peak age has no chance. My rationale was to try to reward both being good and far away from the peak age. I agree that method 1 is not perfect. So that is why I did method 2. Notice there that the best guy is Pedro Martinez at age 28, close to the peak age.
Yes, I could square the age difference. Here are the top 20 from the pitchers with 150+ IP from 19202005
Pitcher YEAR AGE RSAA pts
Roger Clemens 2005 42 53 9053.7197
Dazzy Vance 1930 39 64 6489.9136
Jack Quinn 1928 44 27 6131.8323
Randy Johnson 2004 40 50 6127.245
GrovC Alexander 1927 40 50 6127.245
Lefty Grove 1939 39 54 5475.8646
Randy Johnson 2002 38 62 5100.4238
Nolan Ryan 1991 44 21 4769.2029
Phil Niekro 1978 39 46 4664.6254
Roger Clemens 2004 41 32 4661.9168
Dwight Gooden 1985 20 58 4625.2042
Ted Lyons 1942 41 30 4370.547
Bob Feller 1939 20 51 4066.9899
Jack Quinn 1926 42 23 3928.9727
Phil Niekro 1984 45 15 3873.6735
Randy Johnson 2001 37 59 3842.3691
Phil Niekro 1979 40 30 3676.347
Jack Quinn 1924 40 30 3676.347
Don Drysdale 1957 20 45 3588.5205
Nolan Ryan 1989 42 21 3587.3229
No comments:
Post a Comment