The original version of this article appeared on Baseball Prospectus Wrigleyville.
By Jeff Lamb
It has seemed to me for a number of years that Major League Baseball is getting younger. Could you imagine, just a few years back, a hot prospect promotion engendering more fan interest than a marquee free-agent signing? It happens these days. I recently wondered, though, whether the big leagues' greening is a phenomenon that shows up in data beyond the anecdote, or whether my opinion is being colored by the youth movement that has been in process for the last half-decade at Wrigley Field.
In an effort to determine whether MLB is actually getting younger, I analyzed the average age of Major League players over the past 50 years, and compared the trends I found there to the aging patterns for the Cubs, alone.
Here's what I found: The current period appears to be a continuation of a long trend that can be fairly easily explained by medical science -- which is that players today play longer, and into later years, than they did in the '60s and '70s. The data is skewed, however, due to a period of time from 1997 to 2007 when players received extra (ahem) assistance from medical science. That makes the short-term trend, yes, downward.
In 1965, the average age of a Major League hitter was 27.3 years old, and that of a pitcher was 27.7. Those values fluctuated slightly from year to year with a gradual upward slant until 1997, when statistically significant increases were common, driving the average ages for hitters and pitchers as high as 29.3 and 29.2, respectively, in 2005. As shown in the chart, the shape of the increase in age of pitchers is similar to that of hitters, but overall, hitters stayed in the game longer than pitchers, the reasons for which likely have to do with arm injuries.
Assuming that the "steroid era" will indeed prove to be an outlier on the chart, the average age of hitters in MLB does seem to be in decline back to normal (post 1980) levels, though it remains to be seen whether this is just a reversion to the mean. To this point, the average age has simply retraced the questionable increases seen from 1997-2007 and has found the level that has been experienced most frequently since 1980 (28.5).
Because the focus on young players has been so obvious at Wrigley Field, I also analyzed the average age of Cubs players over the same period of time and noticed some undeniable trends.
Over the last 50 years, the Cubs have typically been older than the MLB average. Only 20 times out of 50 were the Cubs younger than average for pitchers and hitters combined (groups given equal weight). Recent history shows a heavy slant toward older players, as evidenced by having a team older than average in 13 out of 15 years from 1996 through 2010. Cubs hitters during that time period were even older, surpassing the average age of the MLB average hitter in all but one season (2006).
The aging of the Cubs was especially egregious during the period of 1998-2004, when Cubs hitters averaged more than 30 years every season. During the same time period, Cubs positional players exceeded the average age of the rest of MLB by an average of 1.5 years.
Since the arrival of the Theo Epstein era, though, the reversal has been dramatic. Each of the last four seasons has seen Cubs players end up younger than the MLB average, and the differential in average age has become significant, especially for the hitters. Prior to the arrival of Epstein, only four times out of 46 seasons had Cubs hitters been younger than the average age of MLB hitters by more than 0.5 years. Each of the last four seasons has seen that mark surpassed, with 2014 and 2015 being the largest such figures posted, at 1.7 and 1.5 years below MLB average, respectively.
In 2008, Cubs hitters averaged 30 years old, and the pitching staff averaged 29. In 2015, the pitchers had roughly the same average age, but the average age of the hitters was down to 26.9. The Cubs don't have the youngest team in baseball -- their pitching staff was actually one of the oldest, on average, bringing them up to the eighth-youngest team in MLB, while their positional players check in at third youngest.
This front office has made it clear that it will continue to blend young talent with established veteran leadership. The older veterans play an important role in teaching the young talent how to be professional ballplayers, but their presence greatly impacts these average-age figures, and masks how young this core truly is. For example, replacing David Ross with Willson Contreras would bring the average age of the hitters down by over one whole year!
Even though the core has come to the Majors together, for the most part, it is quite likely that the average age will not begin to creep up significantly for a couple of years. Older players such as Ross, Jason Hammel, John Lackey and Miguel Montero will likely not be a part of the team longer than two seasons, and it is possible that they will be replaced with homegrown talent, further de-aging the roster.
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Jeff Lamb is a financial professional with over ten years of experience. Occasional baseball writer and novelist.