Posted by Jeff Lubbers on Wednesday, February 10, 2010 at 6:00 am

Don’t get me wrong – I find the latest and greatest defensive metrics as interesting as the next baseball stathead.  Though I’m still in the process of understanding all of them, at the very least I am thrilled that metrics other than errors and fielding percentage exist to gauge defensive proficiency.  Now that these statistics are gaining acceptance throughout the baseball community one of the results is the impact it is having on the aging and defensively challenged slugger.  If I didn’t know any better I would have thought that Jack Cust is right now be holding a sign that reads “Will Walk, Whiff, or Slug for Food.”

To hear the well-respected website FanGraphs tell the story, the notion of American League teams employing a single designated hitter is in the process of being phased out in favor of a DH-by-committee approach.  One of the benefits to taking this approach is to have a way to give a variety of a team’s positional players a day off in the field and instead of his normal defensive position penciling him in at designated hitter.  By taking this group approach teams apparently no longer have a need for the stereotypical aging designated hitter who may no longer be very adept in the field.

However, when looking all the way back to 1973 (when the designated hitter was first used) it becomes clear that during the life of the designated hitter the majority of teams have not primarily used one player in that position over the course of a season.  The graph below counts in each year how many players who qualified for the batting title made at least half of their plate appearances as a designated hitter.

Overall it does not seem like there is a very different story to be told in the last couple of years than what has been done in the last few decades.  In 2009 there were 6 such players, which was actually up from 4 players in 2008.  In fact the number of such players was higher in only two seasons going all the way back to 1999.  If anything a shift in how teams used the designated hitter took place over a decade ago, as in the mid-1990’s the majority of American League teams were primarily using a single designated hitter while in recent years no more than half of the fourteen teams take such an approach.

The baseball blogosphere is not the only place where the idea of aging players being phased out of the game is taking hold.  Tom Verducci of SI.com recently wrote about how teams are now valuing defense much more and how that is hurting the older free agents who in years past might have commanded more highly valued contracts.  Again, defense is supposedly taking precedent over those who can still hit but can not field as much.

Verducci uses a few quick and easy statistics to prove his point, one being that only 6 players 36 years or older took more than 400 at bats in 2009, down from 13 in 2008 and an average of 11 in the three prior years.

However, what Verducci seems to believe is a trend again seems to be much ado about nothing.  Using the slightly more accurate number of plate appearances by players age 36 and older it seems that the number of such players obtaining more than 400 plate appearances was down a bit in 2009 but not quite enough to make a claim that the older players of the game are fading away.  The graph below counts the number of such players going back to 1990.

In 2009 there were 13 such players compared to either 17 or 18 in each year from 2004 to 2008.  Can we attribute the drop to a widespread trend throughout baseball or to a slight blip that will likely even out in future years?  I am guessing the latter.

Furthermore, looking at the numbers of these “ancient” players shows that teams are not devaluing aging players who trip over themselves in the field but merely devaluing mediocre hitters.  The chart below looks at the batting average, on-base percentage, slugging percentage, and resulting OPS of all players 36 years or older who obtained more than 400 plate appearances in a season.

	Batting Average	On-Base Percentage	Slugging Percentage	OPS
2009	.258	.341	.438	.779
2008	.286	.370	.479	.850
2007	.275	.361	.452	.813
2006	.272	.345	.434	.779
2005	.269	.343	.429	.772
2004	.280	.365	.483	.848
2003	.284	.370	.477	.847
2002	.276	.364	.473	.837
2001	.272	.359	.471	.830
2000	.287	.376	.460	.836
1999	.300	.388	.467	.855
1998	.286	.357	.447	.804

 

 In 2009 these players posted a lower OPS in all seasons going back to the latest round of expansion in 1998 save for a single season (2005).  It seems that instead of deciding that aging players are not valuable simply because of their age, teams are deciding that at least in 2009 these players just are not as good of players when compared to their counterparts in previous seasons.  Teams are not making a conscious decision to go with younger players – they are simply choosing the best players regardless of age.

The final chart below shows the average batting age of all players who made plate appearances in 2009.  Looking at these numbers it does not seem like much changed in 2009 or changed much in any recent year.

Year	Batting Age
2009	28.8
2008	28.8
2007	29.1
2006	29.2
2005	29.2
2004	29.3
2003	29.2
2002	29.2
2001	29.2
2000	29.1
1999	28.9
1998	28.9

 

 The average age of all baseball players will always fluctuate some from year to year but to say that a slight increase or decrease in numbers is representing a shift in baseball is often short-sighted.

*Thanks as always to the folks at Baseball Reference for their invaluable Play Index*

Photo courtesy of www.picapp.com