I think everyone agrees the White Sox haven’t had the year they wanted. So, at present, they’re probably not too keen on celebrating individual accomplishments, but I don’t care, because I’m not them, and because I need material to write about. Therefore! Take a look at Adam Eaton’s player page. There’s something kind of weird that might jump out to you. Eaton as a regular last year was worth 3.6 WAR. Eaton as a regular this year is looking to push 5 WAR. That on its own isn’t real crazy for a 27-year-old, but look over at some other columns. Compared to last year, Eaton has hit worse. Compared to last year, Eaton has run the bases worse. Still, his value has gone up.

That’s because of his defense. What’s funny there, too, is that Eaton moved over to right field from center. So he’s handled a less-important position, but he’s been absolutely fantastic in the corner. Part of what’s happened is that Eaton has shown exceptional range. Yet that doesn’t come close to being a full explanation. You probably know that we have UZR on the site, and we also display many of its components. One of those components is ARM rating, and we have that information going back to 2002. Here are the top 10 player-seasons in ARM per 1,000 innings, for outfielders with at least 750 innings played on the grass. (As you understand, this season isn’t yet over.) (Just, be cool.)

That should go to show you how good Eaton has been. And now, I want to show you another table. I looked at every outfielder who played at least 750 defensive innings in the outfield for two years in a row. Here are the biggest year-to-year ARM-rating improvements:

If the season ended now, Eaton would officially rank first in the table. The season actually has a whole lot left — perhaps to the White Sox’ collective chagrin — but Eaton is still positioned well. He’s never had strong ARM numbers before. Now he’s having one of the best ARM seasons on record.

You don’t have to get too complicated with things. How can you explain these numbers? According to stats at Baseball-Reference, Eaton has been one of the best right fielders in terms of holding baserunners. He’s also held a lot of runners when he’s shifted over to center for occasional spells. And the thing you most closely associate with ARM rating is the outfield assist. Eaton leads all outfielders with 16 assists. Nobody else has more than 12. That kind of gap gets you a big positive number.

In the past, according to the Fan Scouting Report, Eaton wasn’t perceived to have a real strong arm. However, Eaton’s arm did eclipse 100 miles per hour on a throw in 2015. The strength was there, and it stands to reason Eaton this year has gotten more accurate. He might’ve also gotten better about his anticipation and his attack angles. This throw right here is a thing of beauty:

Of course, ARM success can also be tied to bad baserunning decisions:

…so it’s a noisy stat. Runners learn, and assists can come down to fractions of a second. There’s plenty of luck involved, to fold in with the skill. Adam Eaton might not actually have one of the most valuable arms in recent baseball history, but that arm has had a strong season. Most strong seasons are about both skill and luck.

Adam Eaton used to be a center fielder of questionable defensive adequacy. Now he’s a right fielder who looks more comfortable than perhaps any other right fielder. He’s done well to improve his angles, but even more importantly, Eaton’s arm has been playing incredibly well. It’s not close to enough to salvage the White Sox’ disappointing season, but Eaton, overall, has been among the least of their problems.