Changes in WAR and Playing Time Based on Age Since 1980

by
July 22, 2019

In my piece last week discussing the age-related demographics of the Trade Value Series, I included multiple graphs showing how baseball has changed over the years with respect to the quality and quantity of the contributions of younger and older players in the game. This is is one of the graphs from that piece:

This graph, and the others like it in the post, did a good job of showing age-related changes. But I thought there might be interest in the data underlying those graphs, data that would have been much too cumbersome to include in the piece. Below is the data that drove those graphs; it even breaks the ages down into smaller subsets. The numbers in all of the headers below represent player ages.

First, here’s the share of position player WAR by age since 1980. In the graphs included in the piece, I used five-year rolling averages to better assess trends, and only used three age groups. The table below shows the individual season shares, with the prime years and aging years broken down into more groups:

Share of Position Player WAR By Age: 1980-2019
Year 24 and Under WAR 25-27 WAR 28-30 WAR 31-33 WAR 34+ WAR
1980 14.0% 30.7% 27.3% 21.1% 6.8%
1981 13.2% 31.1% 25.9% 18.3% 11.5%
1982 14.4% 29.9% 19.8% 22.6% 13.3%
1983 14.6% 32.4% 23.3% 15.1% 14.6%
1984 21.8% 26.5% 27.3% 14.6% 9.9%
1985 13.5% 31.9% 26.6% 11.9% 16.1%
1986 11.6% 34.4% 24.6% 15.7% 13.7%
1987 15.9% 35.8% 23.3% 15.1% 9.9%
1988 19.8% 29.1% 25.9% 17.9% 7.2%
1989 12.0% 28.9% 33.9% 17.8% 7.3%
1990 10.7% 33.3% 30.1% 15.8% 10.0%
1991 12.0% 29.3% 29.9% 18.1% 10.6%
1992 17.8% 28.5% 25.8% 19.9% 8.0%
1993 12.3% 31.7% 29.1% 17.2% 9.7%
1994 4.9% 32.7% 32.7% 16.0% 13.6%
1995 6.8% 31.9% 34.3% 17.9% 9.1%
1996 8.3% 21.6% 31.8% 27.5% 10.8%
1997 9.0% 20.2% 36.3% 24.8% 9.7%
1998 14.8% 18.9% 30.2% 23.6% 12.5%
1999 8.3% 28.8% 23.4% 24.5% 15.0%
2000 8.4% 27.2% 28.8% 20.0% 15.6%
2001 7.3% 29.3% 29.7% 19.8% 14.0%
2002 7.0% 28.2% 29.5% 20.0% 15.2%
2003 7.8% 30.8% 26.1% 18.4% 16.9%
2004 11.5% 24.4% 33.6% 16.2% 14.3%
2005 10.4% 26.1% 33.5% 19.9% 10.1%
2006 15.1% 25.5% 30.8% 16.5% 12.1%
2007 20.4% 24.8% 23.7% 22.0% 9.0%
2008 15.8% 26.9% 27.8% 15.6% 13.9%
2009 12.4% 33.5% 26.1% 16.3% 11.7%
2010 15.3% 28.9% 26.3% 18.1% 11.5%
2011 15.2% 34.0% 31.5% 10.5% 8.7%
2012 10.9% 29.1% 35.5% 16.7% 7.8%
2013 15.1% 33.4% 31.6% 13.2% 6.7%
2014 17.6% 27.4% 30.8% 17.2% 7.0%
2015 21.5% 27.4% 28.0% 16.4% 6.7%
2016 21.1% 27.7% 27.9% 16.3% 7.0%
2017 19.1% 33.8% 26.6% 15.9% 4.5%
2018 16.8% 38.2% 28.1% 9.4% 7.5%
2019 18.1% 36.6% 29.6% 11.2% 4.4%
Average 13.6% 29.5% 28.7% 17.6% 10.6%

Here’s the share of plate appearances:

Share of Plate Appearances By Age: 1980-2019
Year 24 and Under PA 25-27 PA 28-30 PA 31-33 PA 34+ PA
1980 16.3% 29.6% 26.7% 18.7% 8.8%
1981 13.7% 28.9% 27.0% 19.8% 10.6%
1982 16.1% 27.6% 22.8% 20.7% 12.8%
1983 17.4% 27.0% 23.9% 16.4% 15.3%
1984 19.8% 25.0% 23.4% 15.7% 16.0%
1985 15.6% 29.2% 23.6% 13.0% 18.5%
1986 16.1% 30.8% 22.2% 14.3% 16.7%
1987 18.1% 32.2% 22.4% 14.0% 13.3%
1988 17.1% 31.0% 26.0% 14.7% 11.1%
1989 14.2% 29.9% 29.1% 17.0% 9.7%
1990 13.3% 30.5% 29.5% 15.4% 11.3%
1991 15.2% 29.7% 27.4% 16.5% 11.3%
1992 18.0% 27.5% 25.2% 19.4% 9.9%
1993 14.6% 30.8% 27.0% 17.1% 10.5%
1994 10.3% 31.4% 29.0% 18.1% 11.2%
1995 12.6% 31.5% 26.8% 17.3% 11.8%
1996 12.5% 27.2% 27.2% 21.4% 11.6%
1997 11.9% 26.1% 28.9% 21.0% 12.0%
1998 16.2% 22.6% 27.8% 20.2% 13.2%
1999 15.1% 24.9% 25.1% 19.9% 15.0%
2000 13.3% 25.0% 24.7% 21.1% 15.8%
2001 11.7% 28.8% 23.7% 19.6% 16.1%
2002 11.6% 26.8% 26.5% 19.0% 16.2%
2003 10.0% 29.5% 25.7% 18.4% 16.2%
2004 11.2% 25.3% 29.5% 17.7% 16.4%
2005 12.5% 23.0% 28.1% 20.5% 15.9%
2006 15.3% 22.6% 26.6% 18.1% 17.4%
2007 16.3% 24.4% 22.3% 22.2% 14.9%
2008 17.4% 25.7% 23.1% 18.0% 15.8%
2009 11.9% 30.5% 24.3% 19.4% 13.8%
2010 14.6% 28.8% 23.4% 16.8% 16.3%
2011 15.4% 28.8% 24.3% 16.7% 14.9%
2012 13.7% 28.9% 28.2% 17.0% 12.2%
2013 16.0% 29.7% 25.7% 16.4% 12.1%
2014 17.1% 27.0% 27.1% 18.3% 10.6%
2015 17.4% 26.3% 26.0% 20.0% 10.3%
2016 16.3% 28.4% 26.2% 19.2% 9.9%
2017 17.7% 30.5% 23.2% 18.4% 10.2%
2018 16.2% 33.3% 24.5% 15.9% 10.1%
2019 15.6% 33.5% 25.7% 16.3% 8.9%
Average 14.9% 28.3% 25.8% 18.0% 13.1%

And here’s the quality of those plate appearances with WAR per 600 plate appearances.

WAR Per 600 Plate Appearances By Age: 1980-2019
Year 24 and Under WAR/600 25-27 WAR/600 PA 28-30 WAR/600 PA 31-33 WAR/600 PA 34+ WAR/600 PA
1980 1.6 1.9 1.9 2.1 1.4
1981 1.8 2.0 1.8 1.7 2.0
1982 1.6 2.0 1.6 2.0 1.9
1983 1.6 2.2 1.8 1.7 1.8
1984 2.0 2.0 2.1 1.7 1.1
1985 1.6 2.0 2.1 1.7 1.6
1986 1.3 2.1 2.0 2.0 1.5
1987 1.6 2.0 1.9 2.0 1.4
1988 2.1 1.7 1.9 2.3 1.2
1989 1.6 1.8 2.2 1.9 1.4
1990 1.5 2.0 1.9 1.9 1.6
1991 1.5 1.8 2.0 2.0 1.7
1992 1.8 1.9 1.9 1.9 1.5
1993 1.5 1.9 2.0 1.8 1.7
1994 0.9 1.9 2.0 1.6 2.2
1995 1.0 1.8 2.3 1.9 1.4
1996 1.2 1.4 2.1 2.3 1.7
1997 1.4 1.4 2.3 2.1 1.5
1998 1.7 1.5 2.0 2.1 1.7
1999 1.0 2.1 1.7 2.2 1.8
2000 1.1 2.0 2.1 1.7 1.8
2001 1.1 1.9 2.3 1.8 1.6
2002 1.1 1.9 2.0 1.9 1.7
2003 1.4 1.9 1.8 1.8 1.9
2004 1.9 1.7 2.1 1.7 1.6
2005 1.5 2.1 2.2 1.8 1.2
2006 1.8 2.1 2.1 1.7 1.3
2007 2.3 1.8 1.9 1.8 1.1
2008 1.7 1.9 2.2 1.6 1.6
2009 1.9 2.0 2.0 1.5 1.6
2010 1.9 1.8 2.1 2.0 1.3
2011 1.8 2.2 2.4 1.2 1.1
2012 1.5 1.9 2.3 1.8 1.2
2013 1.7 2.1 2.3 1.5 1.0
2014 1.9 1.9 2.1 1.7 1.2
2015 2.3 1.9 2.0 1.5 1.2
2016 2.4 1.8 2.0 1.6 1.3
2017 2.0 2.0 2.1 1.6 0.8
2018 1.9 2.1 2.1 1.1 1.4
2019 2.1 2.0 2.1 1.3 0.9
Average 1.6 1.9 2.0 1.8 1.5

Pitchers were only touched on in my piece because the trends weren’t as striking as with position players, but the table below shows the pitcher share of WAR by age over the years:

Share of Pitcher WAR By Age: 1980-2019
Season 24 and Under WAR 25-27 WAR 28-30 WAR 31-33 WAR 34+ WAR
1980 24.1% 26.2% 21.2% 11.7% 16.9%
1981 20.9% 28.1% 20.7% 12.1% 18.1%
1982 18.2% 30.7% 19.9% 12.1% 19.1%
1983 18.4% 29.6% 27.2% 9.3% 15.6%
1984 21.6% 29.3% 26.4% 9.9% 12.8%
1985 22.2% 29.7% 23.0% 12.6% 12.5%
1986 20.4% 31.8% 20.6% 16.0% 11.2%
1987 19.2% 26.8% 23.9% 18.4% 11.7%
1988 18.6% 31.7% 20.3% 16.8% 12.7%
1989 17.3% 29.0% 23.8% 17.4% 12.4%
1990 17.2% 34.5% 21.0% 15.4% 11.9%
1991 19.7% 29.0% 24.8% 14.2% 12.3%
1992 17.4% 31.6% 24.4% 12.5% 14.0%
1993 13.7% 32.0% 29.1% 15.1% 10.0%
1994 13.1% 30.4% 27.0% 23.4% 6.1%
1995 10.5% 30.3% 29.7% 19.3% 10.2%
1996 12.8% 24.6% 30.9% 21.0% 10.6%
1997 14.9% 25.3% 28.6% 15.7% 15.5%
1998 12.9% 25.4% 24.9% 21.2% 15.7%
1999 16.9% 25.9% 19.9% 21.7% 15.5%
2000 16.1% 22.4% 25.7% 17.3% 18.5%
2001 22.0% 18.0% 25.8% 15.6% 18.6%
2002 17.1% 27.4% 22.1% 14.2% 19.2%
2003 18.2% 28.7% 21.7% 14.8% 16.7%
2004 12.2% 31.7% 24.1% 15.1% 16.9%
2005 18.5% 27.8% 22.9% 14.9% 15.8%
2006 20.3% 28.2% 23.4% 10.0% 18.1%
2007 17.0% 28.4% 27.9% 11.8% 14.8%
2008 23.0% 30.2% 23.1% 15.6% 8.1%
2009 17.2% 38.7% 20.6% 13.9% 9.6%
2010 20.2% 37.3% 17.6% 15.7% 9.2%
2011 17.7% 36.2% 23.9% 9.7% 12.4%
2012 18.0% 32.4% 23.7% 12.6% 13.3%
2013 18.0% 34.6% 26.3% 10.4% 10.6%
2014 15.6% 33.0% 33.7% 9.2% 8.4%
2015 15.7% 36.8% 25.7% 14.7% 7.1%
2016 17.2% 33.8% 27.0% 17.0% 5.0%
2017 17.1% 26.1% 31.2% 19.0% 6.6%
2018 15.0% 29.0% 30.2% 16.8% 9.1%
2019 12.1% 29.3% 27.4% 18.7% 12.4%
Average 17.5% 29.8% 24.8% 15.1% 12.9%

If you eyeball the data, it certainly looks like older pitchers are more valuable as the run-scoring environment tips in batters’ favor. It’s possible the younger pitchers simply aren’t quite as ready for the step up to the big leagues when offense is at its highest. The next table shows the share of innings pitched by age group.

Share of Innings Pitched By Age: 1980-2019
Season 24 and Under IP 25-27 IP 28-30 IP 31-33 IP 34+ IP
1980 22.1% 30.0% 22.5% 12.7% 12.6%
1981 17.9% 33.4% 20.9% 13.7% 14.1%
1982 16.4% 34.0% 21.9% 13.4% 14.3%
1983 17.6% 31.5% 24.7% 12.1% 14.2%
1984 18.7% 31.1% 26.1% 12.0% 12.1%
1985 19.0% 30.3% 24.6% 13.8% 12.3%
1986 19.1% 31.6% 21.4% 16.0% 11.9%
1987 20.4% 29.0% 22.8% 17.2% 10.7%
1988 18.5% 28.9% 23.0% 17.4% 12.1%
1989 17.0% 27.3% 25.6% 16.7% 13.4%
1990 17.0% 29.5% 26.2% 16.1% 11.2%
1991 19.1% 29.9% 23.5% 15.8% 11.7%
1992 17.5% 30.1% 24.5% 13.9% 14.0%
1993 17.3% 32.0% 25.2% 13.9% 11.7%
1994 15.8% 30.6% 24.8% 18.0% 10.8%
1995 16.6% 32.0% 26.7% 15.0% 9.7%
1996 16.4% 30.2% 28.3% 15.9% 9.1%
1997 17.3% 29.9% 26.1% 14.4% 12.3%
1998 15.9% 28.2% 24.6% 18.3% 13.1%
1999 18.8% 25.3% 22.8% 20.3% 12.8%
2000 17.7% 25.2% 24.5% 18.3% 14.2%
2001 21.4% 22.6% 24.6% 16.9% 14.5%
2002 18.4% 28.4% 22.8% 14.9% 15.5%
2003 18.0% 30.0% 22.8% 14.5% 14.7%
2004 13.0% 32.0% 22.8% 16.5% 15.7%
2005 16.8% 27.7% 24.3% 15.1% 16.1%
2006 20.8% 26.6% 23.8% 12.7% 16.1%
2007 18.5% 28.0% 28.4% 10.6% 14.5%
2008 19.8% 32.1% 22.0% 14.0% 12.1%
2009 18.0% 35.2% 20.3% 14.3% 12.2%
2010 17.7% 35.3% 19.2% 16.3% 11.5%
2011 17.4% 34.1% 23.1% 12.4% 13.1%
2012 17.0% 32.4% 25.1% 12.8% 12.7%
2013 16.9% 32.3% 27.6% 10.7% 12.5%
2014 15.7% 30.7% 28.7% 13.9% 10.9%
2015 15.6% 33.1% 25.0% 15.2% 11.1%
2016 15.6% 32.7% 25.2% 19.0% 7.4%
2017 15.9% 29.0% 28.5% 17.6% 9.0%
2018 14.1% 32.2% 27.1% 16.9% 9.8%
2019 12.2% 32.0% 28.0% 17.0% 10.7%
AVERAGE 17.5% 30.4% 24.5% 15.2% 12.5%

The table is somewhat similar to the first one. Perhaps the most interesting part of the pitchers comes from the quality of pitching by age, as seen below.

WAR Per 200 IP By Age: 1980-2019
Season 24 and Under WAR/200 IP 25-27 WAR/200 IP 28-30 WAR/200 IP 31-33 WAR/200 IP 34+ WAR/200 IP
1980 2.1 1.7 1.8 1.8 2.6
1981 2.3 1.7 1.9 1.7 2.5
1982 2.2 1.8 1.8 1.8 2.6
1983 2.1 1.9 2.2 1.5 2.2
1984 2.3 1.9 2.0 1.6 2.1
1985 2.3 1.9 1.8 1.8 2.0
1986 2.1 2.0 1.9 2.0 1.9
1987 1.9 1.8 2.1 2.1 2.2
1988 2.0 2.2 1.7 1.9 2.1
1989 2.0 2.1 1.8 2.1 1.8
1990 2.0 2.3 1.6 1.9 2.1
1991 2.0 1.9 2.1 1.8 2.1
1992 2.0 2.1 2.0 1.8 2.0
1993 1.6 2.0 2.3 2.2 1.7
1994 1.6 2.0 2.2 2.6 1.1
1995 1.2 1.9 2.2 2.5 2.1
1996 1.5 1.6 2.2 2.6 2.3
1997 1.7 1.7 2.2 2.2 2.5
1998 1.6 1.8 2.0 2.3 2.4
1999 1.8 2.0 1.7 2.1 2.4
2000 1.8 1.8 2.1 1.9 2.6
2001 2.0 1.6 2.1 1.8 2.5
2002 1.8 1.9 1.9 1.9 2.5
2003 2.0 1.9 1.9 2.0 2.2
2004 1.9 2.0 2.1 1.8 2.1
2005 2.2 2.0 1.9 2.0 2.0
2006 1.9 2.1 1.9 1.6 2.2
2007 1.8 2.0 1.9 2.2 2.0
2008 2.3 1.9 2.1 2.2 1.3
2009 1.9 2.2 2.0 1.9 1.6
2010 2.3 2.1 1.8 1.9 1.6
2011 2.0 2.1 2.0 1.6 1.9
2012 2.1 2.0 1.9 2.0 2.1
2013 2.1 2.1 1.9 1.9 1.7
2014 2.0 2.1 2.3 1.3 1.5
2015 2.0 2.2 2.0 1.9 1.3
2016 2.2 2.0 2.1 1.8 1.3
2017 2.1 1.8 2.2 2.1 1.5
2018 2.1 1.8 2.2 2.0 1.9
2019 2.0 1.8 1.9 2.2 2.3
Average 2.0 1.9 2.0 2.0 2.0

Over time, the quality of pitching is fairly consistent across all age groups and hasn’t changed too much. None of the data above is static. It isn’t necessarily cyclical, but changes in the game affect the ability of older players to compete at a high level and younger player readiness.





 

Craig Edwards can be found on twitter @craigjedwards.

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Cave Dameron
4 years ago

The number of years of control that a team has over a player is ridiculous. Players need to get to free agency sooner or get paid more in the arbitration process/raised league minimum, otherwise we’ll get another strike.

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