Average Age Of The Best Players Over Five Year Periods Since 1947

Using the Baseball Reference Play Index, I found the top 10 and top 25 players in WAR for 5-year time periods starting in 1947. So 1947-51 was the first period. Then 1952-56 and so on. The table below shows these averages. The WAvg columns are the average age weighted by WAR. The two lowest averages for the top 10 were the 1957-61 periods and the 1977-81 periods.

Years	Top 10 Avg	Top 25 Avg	Top 10 WAvg	Top 25 WAvg
1947-51	30.5	29.64	30.15	29.63
1952-56	27.6	29.28	27.33	28.9
1957-61	26.6	27.62	26.59	27.25
1962-66	28.4	27.38	28.72	27.66
1967-71	29.6	28.76	29.9	29.02
1972-76	27.6	28.12	27.68	28.08
1977-81	26.1	27.56	26.25	27.48
1982-86	27.6	28	27.52	27.88
1987-91	29.1	28.32	28.97	28.38
1992-96	27.1	27.92	27.06	27.8
1997-2001	28.1	28.44	28.16	28.46
2002-06	29.8	29.56	29.8	29.74
2007-11	27.85	27.7	27.98	27.75
2012-16	27.12	28.9	27.18	28.54

The good young players from 1957-1961 were

Player	WAR	Avg Age
Hank Aaron	41.3	25
Frank Robinson	30.9	23
Al Kaline	29	24
Rocky Colavito	23.4	25

The good young players from 1977-1981 were

Player	WAR	Avg Age
George Brett	34.3	26
Gary Carter	27.4	25
Andre Dawson	26.4	24
Keith Hernandez	24.9	25
Chet Lemon	24.7	24
Willie Randolph	24.6	24

 
 

This next table shows how many of the players in the top 10 and top 25 had an average age less than 27 in each period. That means 26 or less and would include guys who were 24-25-26-27-28, so at least 2 of their seasons were at age 25 or younger. 1977-81 had six "young" players in the top 10, the most for any period. 1952-56 is second with 5. Both 2007-11 and 2012-2016 have had a large number of young players in the top 25.

Years	Top 10 < 27	Top 25 < 27
1947-51	1	6
1952-56	5	3
1957-61	4	10
1962-66	3	11
1967-71	2	7
1972-76	4	8
1977-81	6	10
1982-86	4	9
1987-91	2	8
1992-96	4	8
1997-2001	3	7
2002-06	1	5
2007-11	4	11
2012-16	2	12

This time line chart shows how many players 25 or younger had a WAR of at least 5 per team each year going back to 1946 (I used 4.75 for 154 game seasons and made similar adjustments for strike years). I did it per team since when there are fewer teams, not as many players will reach a given WAR. Baseball Reference says a WAR of 5 is an All-Star season.

It looks like the rate was pretty high for most of 1955-67. Six of those seasons were at least 0.4 and that mark has been eclipsed in only 2 seasons since then. There has been an upward trend since 2004.

Swings In Pitching Game Scores In Playoff Series Deciding Games, 2007-2016

Suppose pitcher A had an average Game Score (GS) of 50 and pitcher B also had 50. Then in the deciding (last) game of a playoff series, pitcher A had a GS of 60 and pitcher B had 40. That is a swing of 20 since pitcher A did 10 better than normal and pitcher B did 10 worse.

The table below shows the swings for all the deciding games in the world series (WS) and league championships (LCS) from 2007-2016. I did not take into account how good the opposing hitters were, who was pitching at home and how much each pitcher varied in GS from game to game in the given season.

If one pitcher faced better hitters, it would tend to hold down his GS. Maybe pitching at home helps. And maybe some pitchers had a higher standard deviation in GS's in the given season. That could explain part of the swings.

The first pitcher listed is the one who exceeded his average season GS by the most in the deciding game (or fell short by the least). Kershaw has two of the three biggest swings and they are not in his favor. They are both very large in comparison to most swings.

AvGS is a pitcher's average game score for the season. DecGS is their game score for the deciding game. Diff is how much those two differed. Swing is the difference in the differences for each pitcher.

Year	Series	Pitcher	AvGS	DecGS	Diff	Pitcher	AvGS	DecGS	Diff	Swing
2013	NLCS	Wacha	57.4	77	19.6	Kershaw	66.9	17	-49.9	69.5
2012	ALCS	Scherzer	55.6	69	13.4	Sabathia	58.1	18	-40.1	53.5
2016	NLCS	Hendricks	61.2	80	18.8	Kershaw	70.3	39	-31.3	50.1
2012	NLCS	Cain	60.6	62	1.4	Lohse	56.7	24	-32.7	34.1
2010	ALCS	Lewis	55.6	76	20.4	Hughes	52.1	39	-13.1	33.5
2013	WS	Lackey	55.6	56	0.4	Wacha	57.4	28	-29.4	29.8
2009	ALCS	Pettitte	50.4	60	9.6	Saunders	47.3	29	-18.3	27.9
2015	NLCS	Matz	57.8	54	-3.8	Hammel	54.0	25	-29.0	25.2
2010	WS	Lincecum	57.0	80	23.0	Lee	60.4	59	-1.4	24.4
2008	NLCS	Hamels	58.8	65	6.2	Billingsley	55.8	38	-17.8	24.0
2011	ALCS	Holland	52.0	39	-13.0	Scherzer	50.7	20	-30.7	17.7
2016	WS	Hendricks	61.2	51	-10.2	Kluber	60.4	34	-26.4	16.2
2008	ALCS	Garza	52.8	75	22.2	Lester	54.8	61	6.2	16.0
2007	NLCS	Morales	52.3	49	-3.3	Owings	50.1	33	-17.1	13.9
2011	WS	Carpenter	55.4	55	-0.4	Harrison	52.9	39	-13.9	13.5
2007	WS	Lester	48.2	63	14.8	Cook	48.4	50	1.6	13.2
2009	NLCS	Hamels	51.5	43	-8.5	Padilla	48.2	28	-20.2	11.7
2014	ALCS	Vargas	52.0	63	11.0	Gonzalez	53.6	55	1.4	9.6
2015	ALCS	Ventura	53.1	59	5.9	Price	61.8	59	-2.8	8.7
2010	NLCS	Oswalt	60.9	53	-7.9	Sanchez	57.3	41	-16.3	8.4
2011	NLCS	Jackson	50.8	34	-16.8	Marcum	55.1	31	-24.1	7.3
2009	WS	Pettitte	50.4	47	-3.4	Martinez	52.1	43	-9.1	5.7
2013	ALCS	Scherzer	62.8	56	-6.8	Buchholz	64.6	53	-11.6	4.8
2014	WS	Guthrie	50.2	43	-7.2	Hudson	52.0	41	-11.0	3.8
2008	WS	Hamels	58.8	56	-2.8	Kazmir	49.8	45	-4.8	2.0
2016	ALCS	Estrada	57.0	59	2.0	Merritt	61.0	62	1.0	1.0
2012	WS	Scherzer	55.6	54	-1.6	Cain	60.6	58	-2.6	1.0
2015	WS	Harvey	60.7	71	10.3	Volquez	52.6	62	9.4	0.9
2007	ALCS	Matsuzaka	53.2	50	-3.2	Westbrook	49.4	46	-3.4	0.2
2014	NLCS	Wainwright	62.1	66	3.9	Bumgarner	59.2	63	3.8	0.1