Offensive Production and the Defensive Spectrum

Back before I knew that Sabermetrics existed, Bill James introduced the concept of the defensive spectrum. This orders players by position, roughly as:

DH - 1B - LF - RF - 3B - CF - 2B - SS - C

Players on the right-hand side of the spectrum are valued for their defensive abilities. Thus, in general, players on the left-hand side must be more productive hitters than those on the right-hand side, since they can be more easily replaced.

Now one of the findings of Sabermetrics is that offensive production is mainly controlled by on-base percentage (OBP) and Slugging Percentage (SLG). But to baseball teams really organize themselves this way? After all, this year we've been hearing about productive outs, and how it's sometimes better to have a player that will give himself up for the club rather than one who will get on base. If baseball teams really believed that, then you shouldn't see a correlation between OBP, SLG, and the defensive spectrum. If, however, baseball management really believes that OBP and SLG are important, then you'd expect players on the left-hand side of the spectrum to have higher values.

So how do baseball teams really behave? To find out, I went to Retrosheet, the online keeper of all baseball statistics, and downloaded the 2003 Players By Position data, which gives, among other things, the on-base and slugging percentages for players by position.

I then sorted players by plate appearances (AB+BB, since sacrifices and HBP weren't included in this particular database), and designated the top 30 players at each position (top 14 for DH) as "regulars." This probably might leave out some teams, and double count others, but I didn't check that for this quick study.

Taking these 30 (14) players per position, we can plot their on-base and slugging percentages, to wit:
  versus On-base percentage for 2003 regulars
(clicking on the figure will get you an encapsulated Postscript version of this picture)

It's a little confusing. The outliers (especially Lopez) make things a hard to see. However, it looks as though the first basemen and left fielders, especially, are in the upper right hand corner of the diagram, while shortstops and most catchers are in the lower part.

To make things a little clearer, let's plot the average values of OBP and SLG per position, and the standard deviation in the data for the 30 (14) regulars:
Slugging versus On-base
  percentage for 2003 regulars.  Averages and Standard Deviations

With a couple of exceptions, this pretty much follows the defensive spectrum. There are a few flips. In particular, left fielders are higher than first basemen and designated hitters. (This is mainly due to Barry Bonds, of course.) In the main, however, the defensive spectrum is respected: we've got better hitting/slugging people on the left-hand side of the spectrum, and relatively poor hitters on the right-hand side. Also note that the error bars are rather wide. We can say with reasonable certainty that left fielders are in general better hitters than shortstops, but it's hard to say if DHs or LF are better hitters.

Of course, averages are strongly affected by the outliers, especially Bonds and Lopez. To minimize the effects of the outliers, we'll plot the median OBP and SLG for each position:
Slugging versus On-base
  percentage for 2003 regulars.  Median, minimum and maximum at each
Here the error bars represent the minimum and maximum performance of the "regulars" at each position. (To improve the resolution, the left field maximum, you-know-who, was left off the plot.) Now we pretty much follow the defensive spectrum. The only real difficulty is at third base, which is under-performing compared to center fielders, and even, in OBP, to second basemen. But in general, the hitting ability at each position follows the defensive spectrum.


Despite what some people say, it's apparent from the above that baseball values those who can get on base and get extra-base hits. If that wasn't true, then we'd expect to see ground-ball hitting first basemen whose goal in life was to "advance the runner". In fact, we see first basemen that hit for power, and who, when they don't hit, walk. The only place we see low power, low OBP players is on the right-hand side of defensive spectrum. They're not in baseball because they can hit ground balls to the right side of the infield. They are in baseball because owners value their gloves.



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