Earlier this month, Rangers’ second baseman Jurickson Profar (an early finalist for the All-Name team) made his major league debut, homering in his first PA, only the third time since 1918 that a player under age 20 has done that.

The player on the list above who didn’t homer in his first PA is pitcher Denny McLain, who nonetheless homered in his first game and (as it turned out) for the only time in his career.

After the jump, I’ll look at bit more at these and other precocious players.

Profar is the 3rd player in his age 19 season to debut this year, and the third to make a splash doing so.

The three teenage debuts this year are the most in any season since 1996, and only the 4th time since 1981 with that many. Here’s a chart of teenagers debuting since 1901.

So, fairly constant in the low single digits each year, since the early 1970s. Notable spikes in the Federal League years, during WWII and during the Bonus Baby era. For those unfamiliar, the bonus baby system existed from 1947 to 1965 and was essentially an open market for signing top amateur talent. To provide limits and prevent the richest teams with the deepest farm systems from acquiring the lion’s share of top talent, players signing above a specified contract value had to play on a major league roster. Thus, from the late 40s into the late 60s, there are elevated levels of teenagers in the major leagues just about every year.

But, how well have those players fared in their careers? Was their precociousness a good indicator of their true talent, or might they have been better served with more seasoning in the minors? Following are charts showing the career value of players debuting as teenagers. First for the position players.

This chart is showing percentage of players debuting as teenagers in each decade who compiled career WAR at different levels. Remember that the absolute number of players represented by these percentages has reduced dramatically since the 1960s.

Until the 1990s, over 20% (and up to over 60%) of players debuting as teenagers failed to compile even 1 WAR. That is, they had really short careers. In the 2000s though, all teenage debuts (admittedly, a much smaller absolute number) have compiled at least 1 WAR and two-thirds have passed 10 WAR. So far this decade, one of the four teenagers to debut (Mike Trout) is already over 10 WAR. Conclusion: Since the bonus baby system was scrapped, teams have become much more discriminating in the players they bring up as teenagers. Thus, the few players who do start very young are truly outstanding prospects who generally thrive as big-leaguers.

What’s the story for pitchers?

Prior to the 1970s, the pattern resembles that for hitters with over half the pitchers failing to compile even 1 WAR.

Fast forward to today and we’re still waiting for our first teenage pitcher of this decade.

Of the 16 teenage pitchers to debut since the 1980s, it’s been kind of feast or famine with 4 over 25 WAR but 10 under 10 WAR. Here’s that list

Finally, these are the all-time WAR leaders for players debuting as teenagers. First, the position players.

Not that it changes the ranking order, but Ruth’s overall WAR (hitting and pitching) comes in at a lofty 178.3, first among all players and twenty WAR clear of Barry Bonds in second place.

And, the pitchers.