Insights III: Birth and baseball, with Mike Trout and ... Claudell Washington?


It's good to be born young, better to stay young, and better still to be born younger.

Age ain't nothin' but number, or so they say, but they said that about on-base percentage, too. In 2012 we were reminded just how important age can be as we witnessed the greatest age-19 and -20 seasons by an everyday player in major league history and realized just how significant being that good in such close proximity to one's birth can be.

You've probably seen some version of this list countless times this season (several of those under my byline at, but I'm including it again because it's that remarkable. Here are, by Baseball-Reference's Wins Above Replacement (bWAR is not the end-all of total-value stats, but the most user-friendly in terms of making lists like this one and thus a very handy shortcut), the best age-20 seasons by a hitter in major league history (eventual Hall of Famers in bold):



Mike Trout


Alex Rodriguez


Al Kaline


Mel Ott


Ted Williams


Ty Cobb


Jason Heyward


Vada Pinson


Mickey Mantle


Frank Robinson


Ken Griffey Jr.


Johnny Bench


Sherry Magee


Claudell Washington


Rogers Hornsby


Jimmie Foxx


Roberto Alomar


Of those 17 men, ten are in the Hall of Fame, and two more, Rodriguez and Griffey, have the résumé to join them. Pinson, Magee, and Washington each played 16 or more years in the major leagues and retired with an above-average OPS+ (Magee, a deadball leftfielder, had a 137 career OPS+, Pinson was a centerfielder for Frank Robinson's Reds in the 1960s and retired with 2,757 hits). The other two are Trout and Heyward, the elder of whom won't turn 24 until August.

One might counter by pointing out that the top-17 seasons by players of any single age will include a comparable number of Hall of Famers, the best are the best, after all, but for those cynics, consider the numbers on this list. In 2012 alone, nine players compiled more bWAR than all fifth-best 20-year-olds of all time, who just happened to be Ted Williams and Ty Cobb. Yes, Trout's season was an all-time great, but most of the players above were merely good by league-wide standards. What made them great was that they were that good so soon after their birth.

Griffey's five-win season in 1990 wouldn't rank as the greatest anything if it weren't for the fact that he was just 20 at the time. Twenty hitters were more valuable by that measure in 2012 alone. However five wins above replacement were all it took to make Harper, who ranked 21st in bWAR last year, the most valuable teenager of all time (again, according to that one statistic, but the general point stands), besting seasons by Ott (3.7 bWAR), Griffey (2.9), and Cobb (2.3), who occupy three of the next four spots on that particular list among players in the modern era (along with Edgar Renteria, at 3.1 bWAR, a five-time All-Star who spent 16 years in the major leagues).

One can reach even further back. In October 2011, Baseball Prospectus published a two-part study by Rany Jazayerli on the age of players at the time of the draft. When it came to the relative ages of hitters drafted out of high school, his findings, which were revised and expanded in BP's Extra Innings in April of 2012, were striking. As Jazayerli wrote in Extra Innings, "high school hitters who are particularly young for their draft class," such as Trout and Heyward, who were drafted before their 18th birthdays, "produce a dramatically higher rate of return than their older classmates."

Of course, it's not youth alone that makes these players valuable or that foretells future greatness. It's the ability to compete, at that young age, at the same level as older players. For example, just five players since the end of World War II have qualified for the batting title as teenagers. They are: Harper, Griffey, Robin Yount, Rusty Staub, and Kaline. Yount and Kaline are in the Hall of Fame. Griffey is sure to join them on the first ballot in 2016, and Staub played 23 years in the majors and retired with 2,716 hits and a 124 career OPS+. Answering a quarter-century-old question posed by Bill James, Jazayerli reported that, given identical 10-homer seasons by 20- and 21-year-old players, the 20-year-old can be projected to hit 61 percent more home runs over the course of his career than the player who showed just as much power but was a year older. To quote Jazayerli again, "That's right-61 percent."

Looking at things from the other direction, I took a look at the debut ages of the top 50 hitters in baseball history according to bWAR. The average debut age (using their age as of June 30 of the season in question) of those 50 men was 20, and the average age at which they first qualified for the batting title was 21. Eighteen of those 50 were in the majors as teenagers and just three, three of the top 50 hitters of all time according to bWAR, first qualified for the batting title after the age of 23*, while 40 of the 50 had their first qualifying season at the age of 22 or younger.

*Honus Wagner was 24, Luke Appling and Wade Boggs were both 25.

What Jazayerli's study shows is that, the younger the player in question, the smaller the age-gap between himself and his competition need be to make it meaningful, and Trout and Harper helped illustrate that in 2012. After all, Trout was, per bWAR, more than twice as valuable as Harper in 2012, yet, in light of his age, Harper's season was every bit as impressive. Think about that the next time you take to twitter or the comments section to implore your favorite team to "free" a hitter in his mid or late twenties who is tearing up Triple-A or about the "slow" development of Starlin Castro or Heyward, only one of whom has turned 23. Age may be just a number, but in a sport defined by numbers, it's one that has been greatly undervalued.

Cliff Corcoran is one of SBN's Designated Columnists. His work also appears at Follow him at @cliffcorcoran.

Log In Sign Up

Log In Sign Up

Please choose a new SB Nation username and password

As part of the new SB Nation launch, prior users will need to choose a permanent username, along with a new password.

Your username will be used to login to SB Nation going forward.

I already have a Vox Media account!

Verify Vox Media account

Please login to your Vox Media account. This account will be linked to your previously existing Eater account.

Please choose a new SB Nation username and password

As part of the new SB Nation launch, prior MT authors will need to choose a new username and password.

Your username will be used to login to SB Nation going forward.

Forgot password?

We'll email you a reset link.

If you signed up using a 3rd party account like Facebook or Twitter, please login with it instead.

Forgot password?

Try another email?

Almost done,

By becoming a registered user, you are also agreeing to our Terms and confirming that you have read our Privacy Policy.


You must be a member of to participate.

We have our own Community Guidelines at You should read them.


You must be a member of to participate.

We have our own Community Guidelines at You should read them.




Choose an available username to complete sign up.

In order to provide our users with a better overall experience, we ask for more information from Facebook when using it to login so that we can learn more about our audience and provide you with the best possible experience. We do not store specific user data and the sharing of it is not required to login with Facebook.