2014 WAR Breakdown by Age (WAR, Part 2)

If you haven’t read Part I, you should consider doing so. For those who would prefer not to, this is a reminder of where these numbers came from:

Using FanGraphs’ terrific leaderboard tools, I found statistics for all players who played at each position in 2014. The following numbers apply only to the time spent at that position. Buster Posey, for example, accumulated 462 plate appearances at catcher, 128 at first base, and 9 at DH, so his plate appearances in those amounts are included for those positions in the table below.

For position players, I calculated WAR per 600 plate appearances. For starting pitchers, I used WAR per 150 innings pitched. For relievers, I used WAR per 50 innings pitched. Here is the table:

The table below shows a combination of all position players split into different age groups. The PA% column shows the percentage of plate appearances for each age group out of the total plate appearances for all hitters. As you can see, the 27 to 29 age range had the largest percentage of plate appearances and the “36 and up” group had the lowest. Similarly, the WAR% shows the percentage of total WAR accumulated by each age group. The column labeled “W%-PA%” shows the difference between the WAR% and the PA% columns. A positive difference is good. This means that age group was responsible for a higher percentage of WAR than their percentage of plate appearances.

POSITION PLAYER BREAKDOWN BY AGE

HITTERS	N	PA%	PA	WAR%	W%-PA%	WAR	WAR/600 PA	AVG	OBP	SLG	wRC+
<23	238	9.0%	16518	9.7%	0.7%	55.1	2.0	.247	.303	.384	92
24 to 26	650	24.0%	44181	23.0%	-1.0%	131.1	1.8	.253	.309	.387	94
27 to 29	685	27.8%	51118	31.5%	3.7%	179.7	2.1	.249	.314	.391	98
30 to 32	471	23.3%	42920	26.1%	2.7%	148.6	2.1	.255	.320	.384	99
33 to 35	236	11.4%	21029	10.0%	-1.4%	57.2	1.6	.253	.326	.394	102
36 & up	112	4.4%	8162	-0.3%	-4.7%	-1.6	-0.1	.236	.292	.353	80

 

The meaty production for position players comes in the two age groups spanning ages 27 to 32. Players in this age range accounted for 51.1% of the total plate appearances and 57.6% of the total WAR. This age group didn’t hit as well as the “33 to 35” age group, but accumulated more WAR/600 PA, mainly due to the difference in the defensive component of WAR.

In news that should not surprise anyone, the “36 and up” age group was the worst, accumulating 4.4% of the total plate appearances but finished with -1.6 WAR with a wRC+ of 80.

Have you heard that on base percentage is an “older player’s skill”? Well, this table backs that up, as OBP increases for each age group from the “under 23” group up to the “33 to 35” group. That skill only lasts for so long, though, as offensive production plummets across-the-board in the “36 and up” age group.

STARTING PITCHER BREAKDOWN BY AGE

SP	N	IP%	IP	WAR%	W%-IP%	WAR	WAR/150 IP	ERA	WHIP	K/9	BB/9
<23	35	9.0%	2621.3	8.8%	-0.2%	30.4	1.7	4.03	1.31	7.4	3.1
24 to 26	104	29.9%	8657.0	31.5%	1.6%	108.7	1.9	3.81	1.28	7.3	2.8
27 to 29	68	26.4%	7657.3	31.9%	5.5%	110.0	2.2	3.65	1.23	7.8	2.5
30 to 32	43	17.8%	5167.0	16.7%	-1.1%	57.8	1.7	3.79	1.28	7.4	2.7
33 to 35	26	11.4%	3312.0	6.9%	-4.5%	23.9	1.1	4.04	1.31	6.6	2.6
36 & up	13	5.4%	1577.3	4.2%	-1.3%	14.4	1.4	4.00	1.30	6.8	2.5

 

In the hitter’s breakdown by age, the two most productive age groups spanned the ages from 27 to 32. For starting pitchers, the two most productive age groups were from age 24 to 29, with the “27 to 29” group being the most productive. This “27 to 29” age group had the best ERA, WHIP, and K/9. For starting pitchers, the “36 and up” age group was actually better than the “33 to 35” group, although the sample size was small, including just 13 pitchers 36 and older.

Strikeouts are important for every pitcher and the above chart shows how strikeouts dwindle as a pitcher ages. The “27 to 29” group has a K/9 of 7.8. This drops to 7.4 K/9 for the “30 to 32” group, then to 6.6 K/9 for the “33 to 35” age group.

RELIEF PITCHER BREAKDOWN BY AGE

RP	N	IP%	IP	WAR%	W%-IP%	WAR	WAR/50 IP	ERA	WHIP	K/9	BB/9
<23	50	5.0%	737.3	6.8%	1.8%	5.8	0.4	3.55	1.26	8.7	3.2
24 to 26	178	28.7%	4200.7	27.5%	-1.3%	23.3	0.3	3.58	1.31	8.7	3.7
27 to 29	157	31.5%	4602.3	40.9%	9.4%	34.7	0.4	3.45	1.24	8.8	3.1
30 to 32	90	20.6%	3016.7	11.1%	-9.5%	9.4	0.1	3.72	1.28	8.1	3.2
33 to 35	33	7.2%	1048.0	6.6%	-0.6%	5.6	0.3	3.66	1.27	7.6	3.1
36 & up	29	6.9%	1015.0	7.1%	0.1%	6.0	0.3	3.76	1.27	8.0	3.2

 

For relief pitchers, the bulk of the production is right there in the “27 to 29” age group. This group accounted for 31.5% of the relief pitcher innings and 40.9% of relief pitcher WAR. They also were tops among all groups in ERA, WHIP, and K/9. The next-oldest group of relievers (“30 to 32”) was the worst, accumulating 20.6% of the relief pitcher innings but just 11.1% of relief pitcher WAR. This looks like the age where strikeouts drop precipitously. Relief pitchers aged 27 to 29 averaged 8.8 K/9 as a group, while those in the “30 to 32” age group had just 8.1 K/9.

The information above is the big picture breakdown by age group for all hitters, starting pitchers, and relief pitchers. Part 3 of this series will show the age group breakdown for each position.