THE BOOK--Playing The Percentages In Baseball

Tuesday, April 10, 2012

Do 2B age worse than the typical position?

Dave suggests that that’s possible.

...in the end, we were left with 23 second baseman who were well above average hitters. As a group, these 23 players hit .280/.361/.430 during their 27-29 years, good for a 118 wRC+, so Kinsler fits into the overall average pretty well. Looking at the same 23 players from ages 31-35, the drop-off is pretty severe – the median performance is just .266/.345/.402, or a 103 wRC+, and the corresponding drop in playing time is even more severe; they averaged 574 plate appearances per year from 27-29 but just 347 from 31-35.

There are some guys who beat the norm and continued to be productive into their mid-30s: Lou Whitaker, Bobby Grich, Roberto Alomar, Davey Lopes, Julio Franco, and Ryne Sandberg all posted at least +17.5 WAR during this five year stretch by maintaining their offensive value, and Placido Polanco also topped that mark through his elite glovework and durability. But, there are also a lot of somewhat inexplicable collapses from guys who were really good before they were 30 and pretty lousy afterwards.

Chuck Knoblauch was even better than Kinsler from 27-29 (125 wRC+, +17.8 WAR), but completely fell apart at age 31 and was a replacement level player until age 33, at which point he was out of baseball. Jose Vidro was a very similar hitter to Kinsler through age 29, but his power disappeared and he was also basically worthless after age 31. Jose Offerman went from posting a 110 wRC+ from 27-29 to an 85 wRC+ from 31-35. Dick McAuliffe went from 127 to 98. Jorge Orta went from 114 to 94. Denis Menke from 115 to 91 and didn’t even rack up 900 plate appearances after turning 31.

A 118 wRC+ in 574 PA (and presuming average fielding) is roughly 3.3 WAR for a 2B.  That’s from Dave’s list of his elite 2B from age 27-29 (which, we’ll presume they were 3.5 WAR at age 27, 3.3 at age 28 and 3.1 at age 29).

A 103 wRC+ in 347 PA (and let’s presume a 0.5 win per 162G drop in fielding) is 1.1 WAR for a 2B.  That’s for age 31-35, which we’ll presume is 2.1 at age 31, 1.6 at 32 1.1 at 33 0.6 at 34 and 0.1 at 35.

Dave doesn’t note what they were at age 30, but 2.6 is fine with me.

So, it seems to me that this what we’d actually expect for the typical player, to lose 0.5 wins a year once you hit age 30.

I think what Dave’s list does is really hit home what a loss of 0.5 WAR means each year.

(Now, if Dave’s original list is filled with really good glove men, such that we’re starting with 3.8 WAR 2B instead of 3.3 WAR, then we may be back to the original question.)

Basically, if Dave repeats his study for SS and for 3B, we should see the same kind of results.

Let’s just create a basic model of aging.  I have no idea if this is a good model, but it just provides a framework for discussion.  You have a hitter that is a 118 wRC+ hitter, and he loses 4 points per year (which is roughly 3 runs a year).  That’s for hitting.  And, let’s say he loses 1.5 runs a year (per 162G) on his glove.  So, if he’s an average fielder today, he’s -1.5 runs next year, and -3 runs the year after that.  And, let’s say that you lose 15 PA the next year, then 30 PA the year after that, and 45 the year after that, and so on.  We have this:

wRC+	Fld	PA	WAR
118	0.0	 575 	 3.1 
114	-1.5	 560 	 2.6 
110	-3.0	 530 	 2.1 
106	-4.5	 485 	 1.6 
102	-6.0	 425 	 1.1 
98	-7.5	 350 	 0.7 
94	-9.0	 260 	 0.3

In the last 5 years, that’s an average of 102 wRC+, and an average of 410 PA.  So, I don’t know that it’s terribly surprising that Dave gets the results he gets.

I’d like to be surprised by seeing aging charts for SS and 3B that are noticeably better than those of 2B.