Not long ago, I opined at length on which of B.J. Upton or David Wright is the best prospect in baseball. My conclusion was that Upton, by virtue of his age and starboard positioning on the defensive spectrum, was the more valuable talent. However, one of my caveats in choosing Upton was that he’d need to remain at shortstop to keep him ahead of Wright. Wright’s rather stunning performance since being called up already had me questioning my decision, and now there are noisy rumblings that the Devil Rays will indeed re-position Upton.

Here’s how Upton has spent his time since being called up in early August:

Pos.    Plate Appearances

SS           54
DH           52
3B           16
LF            3
PH            3

While the Rays have deployed Upton most often at shortstop, they’ve hardly been resolute in doing so. What rankles me is letting a premium prospect with a steep defensive learning curve ahead of him fritter away more than 40% of his time as the DH. At least put him somewhere on the field.

The way the Rays have vacillated over Upton’s defensive positioning leads me to believe they plan to move him permanently, and soon. I think it’s a mistake; whatever his limitations, he hasn’t played his way off of shortstop yet. He deserves the chance to do so at the major-league level, but it doesn’t appear he’s going to get it.

The club was fairly conspicuous and public about its recent decision to give Upton some time at third base. That, and the standard shift from short to third, probably portend a future at the hot corner. That’s too bad. Even so, it’s worth considering what the Rays stand to lose, in terms of value maximization, if this is Upton’s future.

Over the last five seasons (2000-2004), here’s the average batting line for all AL shortstops and third basemen:

Pos.           AVG/OBP/SLG

AL SS        .274/.329/.421
AL 3B        .264/.329/.434

As you can see, the shortstops have an advantage in AVG and a deficit in SLG (and, hence, ISO). OBP is a wash. It’s possible to translate batter rate stats into run values (as in, “runs created”-type measure as opposed to RBI or runs scored) by using the formula PA*OBP*SLG*(1-OBP)/(1-AVG). This way, we can assign run values to the league-average shortstop and league-average third baseman. We’ll use 650 plate appearances (roughly what a full-time player will log in a given season) to perform the calculations. Here’s what happens:

Pos.   Avg. Runs/Season
SS           83.2
3B           84.6

That’s alarmingly little difference over the course of season–less than one-and-a-half runs per 650 plate appearances, not at all what I expected to discover. In other words, the offensive bar for Upton, should he be moved to third, will be moved up only 1.4 runs (again, roughly speaking). This doesn’t jibe with what we’ve been taught about the defensive spectrum over the years. The drop in value from shortstop to third base, we’re told, is fairly precipitous. According to these numbers, it’s nothing of the sort.

If Upton’s defensive liabilities at short are even close to what they’re made out to be, then a move to third, a far less critical position in terms of run prevention, appears to be entirely justifiable. The runs saved by shielding his glove at third would almost surely amount to more than 1.4.

This certainly doesn’t alter the notion that a shortstop is more valuable than a third baseman of similar offensive ability, so long as the defensive skills are comparable. However, what it does call into question is the notion that if a player can scrape by defensively at short rather than moving him to third, he’s a net gain there. From the above numbers, it doesn’t appear to be all that more difficult to find an adequate-hitting shortstop than it is to find an adequate-hitting third baseman. The gap in production isn’t that wide, and it’s certainly not wide enough for an organization to countenance poor (or even narrowly sub-optimal) glovework simply to keep a bat at short. Although I don’t have the wherewithal to quantify it right now, it wouldn’t shock me in the least if the defensive run gap between short and third is notably wider than the offensive run gap. A few hours ago, I wouldn’t have thought that to be the case.

Of course, there may be some distorting noise in the numbers. Recent seasons have been somewhat anomalous in terms of shortstop production (the “Age of the Trinity” and all that), but take a gander at these season-by-season breakdowns for the AL shortstop position:

Season              AVG/OBP/SLG

2000              .278/.327/.424
2001              .269/.325/.414
2002              .272/.326/.422
2003              .273/.324/.416
2004              .279/.341/.427

The current season has been the most productive in the last five for AL shortstops. And keep in mind that those number-skewing members of the trinity are mostly no more. Alex Rodriguez is a third baseman, Nomar Garciaparra logged all of 169 plate appearances in the junior circuit this season and Derek Jeter is posting his lowest EqA since ’97. The success of the AL shortstop this season has little to do with those three.

In the case of Upton, it seems a move to third base won’t be all that noxious to his overall value. In fact, once we get a quantifiable grasp on his defensive abilities at the highest level, it may be that he’s more valuable at third than at short. It’s not so much the case any longer, but there was a time when it was a bit of a sabermetric piety to suggest that offense be heavily considered when assigning positions. We’ve learned a great deal about defense in recent years, and we now know that’s not a wise tack. Maybe it was more wrongheaded than we realized.

I certainly don’t want oversell the implications of these numbers, but perhaps a deeper probing of the defensive spectrum is in order. How much difference, in terms of offensive production, is there from position to position, particularly in this age of taller, stronger, faster and more well-conditioned athletes? Have the margins narrowed? Were they ever that wide to begin with? These are all questions we should be addressing.