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Friday, February 22, 2008
Debunking the "Age 27" myth

By Tristan H. Cockcroft

It never ceases to amaze me how people like to cling to old proverbs.

Case in point: "A hitter tends to break out in his age-27 season."

Huh? Am I missing something? Last time I checked, medical science hadn't progressed to the point where we could actually predict with pinpoint accuracy the exact age at which every athlete on the planet hits their physical peak. To put it another way, it's like suggesting a magical "age-27 fairy" comes floating through a baseball player's window, taps him with a magic wand and, POOF, he's an instant home run champion.

As an aside, this being the steroid era, I suppose it's possible this fairy could manifest itself as a "magic pill" a player takes the morning of his 27th birthday. But I've never been one for conspiracy theories; they really take the fun out of the forecasting business.

Back to my point, for us to invest such stock in an idea, one without statistical data -- complete statistical data, not a sprinkling of examples here or there -- is absolutely tomfoolery. We play a statistical game, one based heavily on numbers and probabilities, and the data, quite simply, can either back up or disprove statements.

Fortunately, I'm not a fan of taking a statement like the one mentioned at the top of this story at its word. A fan of the numbers, I find it imperative to check the data myself to unearth the truth (or lack thereof) behind it.

In order to do that, I collected lifetime statistics -- broken down by year and age -- of 100 players from the past decade. The players selected were the ones who hit the most home runs in the past 10 seasons. No, it doesn't cover the entire gamut of players. Still, considering that the age-27 theory is so often applied to the possibility of bursts in a hitter's power, it's a fairly appropriate sampling. Included is every hitter who has hit at least 138 home runs since Opening Day 1998, and that's a fairly generous sample size.

Collecting the data and sorting it by age in each season of each player's career -- determined by his age as of April 1 that year -- I totaled all numbers accrued by those 100 hitters and scaled them to 600 at-bats. That provides a handy comparison of what the average player in the study would have accomplished granted full-time at-bats at that age.

The results:

Age 18-2037.269.7642128.8110
Age 2143.279.8022128.2150
Age 2268.277.8152524.2320
Age 2389.279.8302722.4502
Age 2497.285.8472722.25510
Age 2598.288.8622920.8566
Age 2698.289.8813119.54913
Age 2798.289.8793019.7327
Age 2895.288.8933218.53415
Age 2993.288.8873218.62010
Age 3088.290.8883119.1168
Age 3181.291.8943218.91511
Age 3269.284.8803119.395
Age 3365.284.8672920.453
Age 3456.278.8643119.265
Age 3544.276.8583019.920
Age 3631.269.8523218.911
Age 3724.282.8873417.722
Age 3818.278.8522821.410
Age 39-4225.273.8442821.622
(No.: Number of players in the study of that age group; High: Number of players who set a new career high in home runs; Peak *: Number of players whose career-best home-run season came at that age.)

What the numbers reveal is that players perform better at age 27 than in most other years of their careers, but not all of those other years. For instance, look at the difference between the numbers of 26- and 27-year-olds. Their batting averages were practically identical (both .289, but the 26-year-olds were about four-thousandths of a point better), and 26-year-olds had the better OPS, total home runs and at-bats per home run ratios.

That might lead a few readers to wonder if many of those "age-26" players might actually have turned 27 early in those seasons, perhaps skewing the numbers. Consider, though, that of the 13 players who hit more home runs at age 26 than in any other year of their careers, four celebrated their 27th birthdays before the All-Star break, but six didn't turn 27 until after the season. Totaling the games played by the lot of 13 as 26- and 27-year-olds, only 31.5 percent (655 of 2,083) came after the player turned 27, less than one-third. I'll leave it to you to decide how significant that is, but I'll also remind you of this: If you want to bump the cut-off date to later in the season, for every 26-year-old who hops into the 27-year-old pool, there'll be a 27-year-old who exits that group to join the 28-year-olds.

Those 28-year-olds, by the way, might have the best stat line of the bunch; that is, if the 31-year-olds don't. Suffice to say, from the chart above, it's clear a player's prime runs about six or seven years, from ages 26 through 32.

But returning to my point, isn't this whole exercise designed to determine when a player begins to realize his peak potential? If that's the case -- and I'll argue it is -- targeting 27-year-olds is particularly foolhardy. That age-27 line in the chart above, after all, is one age class that demonstrates almost zero growth over the previous year. There's noticeably better growth in all of the above categories demonstrated by 23-, 25-, 26- and 28-year-olds. I see that 19-point boost in OPS between 25- and 26-year-olds in the chart above and think it's better to pounce a year earlier than at age 27.

And I might go even a step further than that, and snap players in the 23 to 25 age range, assuming appropriate big league experience on their résumés. Check out the chart below, which breaks down those same 100 hitters by 30-, 40- and 50-homer seasons. "First time" marks the first time in a player's career he hit any of those levels; "All instances" is more explanatory, counting any time a player reached one of those plateaus.

First timeAll instances
Age 18-2037300300
Age 2143100200
Age 2268620920
Age 23899501670
Age 2497135025100
Age 259812112941
Age 269879133151
Age 2798113237102
Age 289599045161
Age 299334132111
Age 308824134142
Age 318181135103
Age 32691222293
Age 33652211872
Age 34561001441
Age 35440001131
Age 3631001621
Age 3724100820
Age 3818000310
Age 39-4225000210

That indicates a fairly healthy share of a player's first rise to prominence before turning 26, wouldn't you say? At the very least, it demonstrates that there's no statistical data to suggest players break through offensively at any one particular age. It could come from anywhere between the ages of 24 and 28, depending on the player's experience.

That in mind, let's take a look at some of 2008's breakout candidates from those age groups, among those who currently reside on the low end of the career value curve.

Age 24 "best bets": Jeff Francoeur, Alex Gordon and Jeremy Hermida.
Sleeper: Adam Lind. He raked during his minor league career and has only Reed Johnson and Matt Stairs to overtake for the everyday left-field role.

Age 25 "best bets": Stephen Drew, Edwin Encarnacion and Rickie Weeks.
Sleeper: Jason Kubel. That .300 batting average and .885 OPS he had in 65 games after July 1 bodes well for his chances at a breakthrough.

Age 26 "best bets": Josh Hamilton, Aaron Hill and Kevin Kouzmanoff.
Sleeper: Wilson Betemit. He has 32 homers in 613 at-bats the past two seasons combined and is a better raw talent today than either Jason Giambi or Shelley Duncan.

Age 27 "best bets": Ryan Garko, Austin Kearns and Chad Tracy.
Sleeper: Scott Hairston. He batted .313 with eight homers in his final 26 games last season, and was a .323 hitter with 26 homers in Triple-A ball in 2006.

Age 28 "best bets": David DeJesus, Khalil Greene and Adam LaRoche.
Sleeper: Rick Ankiel. He hit 43 homers between St. Louis and the minors last year. Just watch out for his batting average, which might kill you.

In summation, would I invest a little more stock in a 27-year-old hitter, as the old adage suggests? Sure I would; that's a prime year of a hitter's career. But I'll be as generous to the 24-, 25-, 26- and, yes, even the 28-year-olds.

After all, that magical fairy apparently likes to spread the wealth among youth.

* For the record, in case you're wondering whether players who are only approaching the prime years of their career might have skewed the stats, note that of the 100 players in the study, only 11 have yet to play their age-30 seasons. Carlos Beltran, Eric Chavez, Travis Hafner and Andruw Jones are age-30 players in 2008, with only Miguel Cabrera (24) and Mark Teixeira (27) less than 28 years old as of this coming April 1.

Tristan H. Cockcroft covers fantasy sports for You can e-mail him here.