The Skill And Health Distribution Of 2Bs And 3Bs

Fangraphs once noted that:

"At one time, second baseman and third baseman were both called the same thing – bad defensive shortstops. From there, they were separated into 2B and 3B pools, but the evidence suggests that the crop of players who end up at 3B are better overall players than their 2B brethren."

As the article notes, in 2008, the average MLB 3B hit .266/.336/.436 (.772 OPS), while the average MLB 2B hit .276/.338/.409 (.747 OPS). Both receive a +2.5 run positional adjustment to account for the difficult at fielding their respective positions; in other words, the two positions are historically equivalent in terms of fielding difficulty.

So why the disparity in hitting talent? Why the distribution of better hitters to third base?

It's surely not a distribution based on who is better with the "glove or bat." While MLB 3B hitters (min. 500 PA) over the past 3 seasons hit .270/.341/.438 (.779 OPS) and 2B hitters (min. 500 PA) over the same 3 season sample size hit .278/.341/.416 (.757 OPS), the average 2B (min. 1000 innings) had only a +0.6 UZR/150 compared to a +0.8 UZR/150 for 3B (min. 1000 innings).

Fangraphs postulated that players may be separated into different places on the diamond "based on things that have little to do with their actual skills, and more about a proxy for what kind of package those skills come in. Perhaps there’s a competitive advantage here for a team that’s willing to take a 6′3 or 6′4 plus defender and shift them to second base instead of third base."

Perhaps it is an issue of pure durability. The average 2B (min. 1000 innings) over the past 3 seasons started 277.3 games and played in 290.1. The average 3B (min. 1000 innings) over the past 3 seasons, however, started 263.6 games and played in 277.1. Despite the frailties of Ian Kinsler, Aaron Hill, Chase Utley, Howie Kendrick and Rickie Weeks, 2Bs, on average, saw more time on the field than did 3Bs. Then again, 3Bs have had their share of injured played over the past 3 seasons in Joe Crede, Adrian Beltre, Mike Lowell, Aramis Ramirez, Eric Chavez, Hank Blalock and Troy Glaus.

Any postulations as to the reason for the distribution? Is it, as Fangraphs suggests, something cosmetic, or is there something not quantified in the data at play? Does playing 2B, which requires a player to "go both ways" (more range) in making outs, require a more durable, athletic, healthier type at the helm than does 3B, which generally only requires a player to go to his left in making 80% of his plays? Does a stronger bat equivocate a stronger throwing arm?

Toss in your two cents in the comments.