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Thursday, May 19, 2005

The Graying of the Game

Recently on the SABR-L list there was an interesting discussion on the “graying of the game” that was spawned by a recent article on Baseball Prospectus of the same name by Nate Silver. Unfortunately, I'm not a subscriber so I don't know what Silver had to say. On the SABR list however, this was a discussion centering on the perception that the average player at the major league level is getting older. The speculation was that free agency would tend to lengthen careers and so post 1977 we should see an increase in the ratio of older players to younger players in the game. Of course, other factors to consider are wider demographic trends of the baby boom generation and the impact of steroids, modern medicine, and modern training techniques.

To try and see what’s going on here I created a query in the Lahman database showing the number of active players in each season since 1950 whose debut had been at least 15 years earlier. In other words, I wanted to see how many veteran players there were in each season. Because there were different numbers of teams in the leagues over the course of those seasons I divided the number of veterans by the number of teams to come up with a Veteran Index. Here were the results:


Year # T VI
1950 18 16 1.13
1951 19 16 1.19
1952 15 16 0.94
1953 24 16 1.50
1954 21 16 1.31
1955 34 16 2.13
1956 27 16 1.69
1957 28 16 1.75
1958 24 16 1.50
1959 24 16 1.50
1960 25 16 1.56
1961 25 20 1.25
1962 23 20 1.15
1963 22 20 1.10
1964 25 20 1.25
1965 24 20 1.20
1966 27 20 1.35
1967 26 20 1.30
1968 18 20 0.90
1969 25 24 1.04
1970 26 24 1.08
1971 30 24 1.25
1972 28 24 1.17
1973 33 24 1.38
1974 37 24 1.54
1975 36 24 1.50
1976 39 24 1.63
1977 40 26 1.54
1978 38 26 1.46
1979 49 26 1.88
1980 50 26 1.92
1981 53 26 2.04
1982 60 26 2.31
1983 61 26 2.35
1984 65 26 2.50
1985 68 26 2.62
1986 65 26 2.50
1987 63 26 2.42
1988 60 26 2.31
1989 54 26 2.08
1990 49 26 1.88
1991 50 26 1.92
1992 52 26 2.00
1993 43 28 1.54
1994 42 28 1.50
1995 38 28 1.36
1996 38 28 1.36
1997 43 28 1.54
1998 39 30 1.30
1999 38 30 1.27
2000 52 30 1.73
2001 60 30 2.00
2002 58 30 1.93
2003 70 30 2.33
2004 69 30 2.30

I then graphed both the raw service time and the Veteran Index.




As you can see the Veteran Index declined from around 1955 to 1968 and then steadily increased reaching a peak in 1985 before declining again until 1999 and then took off again through the present.

While I don’t have anything but speculation to back this up, my view would be that the increase after 1968 was due to the combination of better training and the advent of free agency. Particularly in the early 1980s teams tended to award long term contracts to veterans which tended to keep them in the game longer. In the early 1990s the trend moved towards shorter contracts and consequently the Veteran Index dropped. The combination of steroids and advanced training techniques may account for the recent increase. It should be kept in mind, however, that the baby boom generation (born around 1951) would have reached their 15th season around 1987 so it could also simply be an artifact of the larger societal demographics. The recent increase couldn’t be accounted for in the same way however since it would include those in the baby bust generation (born between 1967 and 1979) which is considerably smaller than the boomers.

2 comments:

Studes said...

Hey Dan, I'm not sure that dividing the number of veterans by the number of teams corrects for expansion, but I don't exactly have a better idea. But I do have a question: can you break the data into pitchers and position players?

David said...

You might be interested in this post:

http://www.baseballmusings.com/archives/008682.php