Which league has better defenders at first base?

Quantifying defense at first base is a hard nut to crack. On the surface more often than not it looks like a big man standing in place waiting for balls to be thrown at him. Sometimes, that's all there is to it.

However, there's also protecting the right-field line, making good tags on pickoff attempts, and corralling errant throws. The last aspect is one that has been touched on here and over at FanGraphs, but it's a very difficult thing to measure in a precise fashion. How bad does a throw have to be for us to credit a first baseman's intervention? Do bigger first basemen produce fewer "scoops" because they present a bigger target, leading to fewer off-the-mark throws? Does a first baseman's scooping ability actually affect the confidence of his teammates and the throws he receives?

While attempts to measure this skill have been admirable and far from useless, the subject matter is a bit of a mess. All of that is to say that it's very difficult to produce defensive numbers for first baseman that completely reflect their abilities to contribute in the field.

That being said, we do have the standard set of advanced tools to measure first base defenders and it's worth seeing where those numbers take us. In particular, I got thinking about first basemen in the American League and National League and how they compare defensively.

My initial instinct was to think that American League first basemen might be better in the field than their National League counterparts. The logic behind this hypothesis is that in the AL teams can hide their bat-only first baseman at DH and play someone more competent in their place. But in the NL teams are stuck playing guys like Ryan Howard because there is nowhere else to put them.

However, an intuitive argument could be made for the other side. Teams in the Senior Circuit know that they don't have a place to stash laughably ineffective fielders and as a result only employ players that have at least some competency with the glove. This also seemed like a plausible explanation to me.

Using DRS and UZR I decided to see which league had better first basemen by taking every season since 2003 (when both metrics appeared on FanGraphs) and comparing the average annual total defensive output of each league's first basemen.

There is a slight difference, but given the number of innings all first basemen from either league play annually, it's hardly worth noting.

Another thing worth mentioning here is that in theory the two leagues should have UZR marks exactly opposite of each other, but for some reason in 2014 the numbers aren't symmetrical. This is more likely to be some kind of record keeping error than anything else.

Interestingly, over the last four seasons there is more of a difference between the AL and NL in first base defense.

This is a bit meatier, but on a per inning basis it's still not particularly significant. Also, you could just as easily say that the previous eight years the AL had far superior leatherwork at first base.

When this concept first occurred to me, I thought there was a chance the way the leagues were structured would incentivize a discrepancy in the quality of first base defenders in the AL and NL. At the moment that does not appear to be the case, at least by the metrics available to us.

However, as mentioned above, it's a messy area.

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All statistics courtesy of FanGraphs

Nick Ashbourne is an Editor for Beyond the Box Score. You can follow him on Twitter at @Nick_Ashbourne.