When it comes to the best outfield arms, there's substantive, useful information, and that which is less so.
Say you want to step up for Roberto Clemente. This is easy. Note that Clemente is the all-time leader in assists for a right fielder, and you confirm the conviction that he remains the best right-field arm of all time. Back that up further with the avalanche of anecdotal evidence from, say, David Maraniss' excellent Clemente biography, in which he relives the great one's perfect, no-hop throw to third in Game 2 of the 1971 World Series.
That wouldn't necessarily get you any closer to a substantive answer, though. Besides, Clemente is an easy choice. What does it mean that the active leader for assists from right field is Bobby Abreu? Think you'll be telling Abreu anecdotes to your grandkids? How about noting that Carlos Lee leads all active left fielders?
As is, sabermetrician Bill James noted that outfield assists are inversely related to team performance -- being an outfielder on a bad team is a great way to rack up assist totals. Opportunities aren't evenly distributed, and a mediocre outfielder on a worse team can get more chances to throw people out. This isn't to knock Clemente, even though as great as he was, he did play on some bad Pirates teams early in his career.
When it comes to picking an arrow from the statistical quiver, there are better tools today than just looking at assists. We can evaluate the outfielder's impact on his team's defensive base/out combinations on the balls he gets to. By looking at what the baserunners did and didn't do on balls hit to an outfielder, we can see the impact on a team's overall run expectancy.
It's significant if the baserunners consistently take fewer bases than expected on base hits or outs because it's much more of an everyday phenomenon. It's also something you won't see in your box score.
As I've suggested before, the best way to employ fielding metrics is to reach for the wisdom of a well-informed crowd and see what conclusions command broad support. With that in mind, let's look at last year's tallies from four different arm metrics. We differentiated the outfield positions because each spot presents different challenges.
We'll use Sean Smith's TotalZone, Mitchel Lichtman's UZR, John Dewan's plus/minus and Colin Wyers' fielding runs. These four counting stats don't work entirely the same way, drawing on different data sets -- there isn't 100 percent agreement on all events among data sets -- although they all scale performance to runs. UZR and fielding runs both employ a seasonal definition of average so that every year, average is zero; plus/minus and TotalZone don't, at least not exactly.
There doesn't appear to be a ton of agreement by just looking at the leaders. But digging down the individual leader boards for each stat gives you more common suspects.
Among left fielders, Shelley Duncan's UZR mark is an outlier because of his small sample size, and UZR's second- and third-best throwers are Josh Hamilton (4.9) and Brett Gardner (4.8); TotalZone has Gardner tied for second (with Duncan and Felix Pie).
For right field, there's general agreement between TotalZone and plus/minus that the top three were Shin-Soo Choo, Jeff Francoeur and Jayson Werth. They differed on the order but both ranked Jose Bautista fourth. UZR has that same quartet with Bautista second followed by Choo and Werth.
For center field, Peter Bourjos was one of the three tied for the lead via TotalZone; UZR has fellow small-sample hero Mitch Maier rated second, followed by Alex Rios and Marlon Byrd. Plus/minus had Byrd third behind Shane Victorino.
Based on these metrics, who has the best throwing arm today? Between last year's results and the fact that left fielders generally aren't going to be your better throwers, I think we can narrow this down to a much smaller group.
The problem is that there isn't a slam-dunk champ. We don't have a Clemente or a Jesse Barfield to make this easy -- we have several good choices but no obvious great one. While giving honorable mention to Bourjos, Byrd and Adam Jones, you can narrow this list down to Francoeur or Choo for the best throwing arm based on their performances in the field.
For a pair, the distinction between the two couldn't be starker. Frenchy might have to settle for being his generation's Ellis Valentine, a one-dimensional player whose infrequent flirtations with offensive success have already hampered his ability to rack up bigger defensive numbers. In contrast, Choo is a legitimately excellent all-around player, albeit now one whose relative anonymity is fading for reasons good and bad.
Christina Kahrl covers baseball for ESPN.com. You can follow her on Twitter.