Seems like the last 3 or 4 years there have been a lot of very excellent, very young baseball players in the major leagues.

Seems like, in that time, there has been a lot of talk about all the very excellent young baseball players in the majors, with Mike Trout and Bryce Harper leading the way. But our impressions are sometimes wrong, as analysis of the relevant data can reveal. So, to see if these impressions are right or wrong, I looked at the data.

The data agree, overwhelmingly.

Using Baseball-Reference.com, I looked at the highest-WAR seasons for players 22 and under from the last 40 years. Though rather than using WAR numbers outright, I scaled WAR to 150 games, to adjust for differences in playing time.  Because WAR behaves more like a cumulative statistic, like hits, than a rate statistic, like batting average, this effectively converts it to a rate statistic.  Because rate statistics are untrustworthy over small sample sizes, I only looked at seasons in which the player played in most of the games, so, at least 82 games.

Here are the top 40 such seasons from the last 40 years:

Year	Player	Lg	Tm	Age	G	WAR	WAR/150
2012	Mike Trout	AL	LAA	20	139	10.8	11.7
2015	Bryce Harper	NL	WSN	22	153	9.9	9.7
1996	Alex Rodriguez	AL	SEA	20	146	9.4	9.7
1981	Rickey Henderson	AL	OAK	22	108	6.6	9.2
2013	Mike Trout	AL	LAA	21	157	8.9	8.5
1980	Rickey Henderson	AL	OAK	21	158	8.8	8.4
1998	Alex Rodriguez	AL	SEA	22	161	8.5	7.9
1983	Cal Ripken	AL	BAL	22	162	8.2	7.6
2014	Mike Trout	AL	LAA	22	157	7.9	7.5
2013	Yasiel Puig	NL	LAD	22	104	4.9	7.1
1998	Andruw Jones	NL	ATL	21	159	7.4	7.0
2015	Francisco Lindor	AL	CLE	21	99	4.6	7.0
1991	Ken Griffey	AL	SEA	21	154	7.1	6.9
2010	Jason Heyward	NL	ATL	20	142	6.4	6.8
2003	Hank Blalock	AL	TEX	22	143	6.4	6.7
2012	Giancarlo Stanton	NL	MIA	22	123	5.5	6.7
1982	Tom Brunansky	AL	MIN	21	127	5.6	6.6
2007	Troy Tulowitzki	NL	COL	22	155	6.8	6.6
2015	Manny Machado	AL	BAL	22	162	7.1	6.6
1999	Andruw Jones	NL	ATL	22	162	7.1	6.6
2005	Grady Sizemore	AL	CLE	22	158	6.6	6.3
2015	Carlos Correa	AL	HOU	20	99	4.1	6.2
2015	Mookie Betts	AL	BOS	22	145	6	6.2
2013	Manny Machado	AL	BAL	20	156	6.4	6.2
2001	Albert Pujols	NL	STL	21	161	6.6	6.1
1992	Ken Griffey	AL	SEA	22	142	5.8	6.1
1979	Paul Molitor	AL	MIL	22	140	5.6	6.0
1976	Willie Randolph	AL	NYY	21	125	5	6.0
1981	Tim Raines	NL	MON	21	88	3.5	6.0
1997	Alex Rodriguez	AL	SEA	21	141	5.6	6.0
1978	Robin Yount	AL	MIL	22	127	5	5.9
2008	Evan Longoria	AL	TBR	22	122	4.8	5.9
1987	Barry Bonds	NL	PIT	22	150	5.8	5.8
1977	Chet Lemon	AL	CHW	22	150	5.8	5.8
2002	Austin Kearns	NL	CIN	22	107	4.1	5.7
1978	Jack Clark	NL	SFG	22	156	5.9	5.7
2012	Jason Heyward	NL	ATL	22	158	5.8	5.5
2012	Bryce Harper	NL	WSN	19	139	5.1	5.5
2012	Brett Lawrie	AL	TOR	22	125	4.5	5.4
1979	Lou Whitaker	AL	DET	22	127	4.5	5.3

I then grouped these into 10 groups of 4 years. As it turns out, the period from 2012 to 2015 contains 5 of the top 10, 8 of the top 20, and 14 of the top 40 of these seasons, as shown by these charts. This, when the average group has 1 in the top 10, 2 in the top 20, and 4 in the top 40.

Of course, sometimes a single player produced more than one of these seasons. But these past four years also dominate in terms of the number of different young players on these lists. Here are all the players having top 40 seasons, listed under their 4-year groups, with their overall placements on the list next to their names. I’ve bolded those with top-20 seasons.

1976 – 1979	1980 – 1983	1984 – 1987
Paul Molitor (27)	Rickey Henderson (4, 6)	Barry Bonds (33)
Willie Randolph (28)	Cal Ripken (8)
Robin Yount (31)	Tom Brunansky (17)
Chet Lemon (34)	Tim Raines (29)
Jack Clark (36)
Lou Whitaker (40)

1988 – 1991	1992 – 1995	1996 – 1999
Ken Griffey (13)	Ken Griffey (26)	Alex Rodriguez (3, 7, 30)
		Andruw Jones (11, 20)

2000 – 2003	2004 – 2007	2008 – 2011
Hank Blalock (15)	Troy Tulowitzki (18)	Jason Heyward (14)
Albert Pujols (25)	Grady Sizemore (21)	Evan Longoria (32)
Austin Kearns (35)

2012 – 2015
Mike Trout (1, 5, 9)
Bryce Harper (2, 38)
Yasiel Puig (10)
Francisco Lindor (12)
Giancarlo Stanton (16)
Manny Machado (19, 24)
Carlos Correa (22)
Mookie Betts (23)
Jason Heyward (37)
Brett Lawrie (39)

Again, these past 4 years dominate.

Now that we know for certain that we’re experiencing a very special surge of young talent, the next thing to ask is, why? Has the surge in the amount of free analysis available (on the web and in ESPN in-depth commentary) over the last decade or so allowed parents to self-coach their youngsters more effectively? And is this finally coming to fruition? Or is this just a fluke? Is it a Cuban invasion? Or something else?