The new generation of Major League superstars is heavily concentrated in the outfield with Mike Trout, Bryce Harper, Jason Heyward, and Giancarlo Stanton leading the way—all 23 years old or younger. A great part of their appeal is their exceptional outfield defense, but the attention there tends to be on range. Heyward and Trout, especially, cover an incredible amount of ground. They were first and third in Plus/Minus Runs Saved among all outfielders in 2012. Plus/Minus Runs Saved is the range component of Defensive Runs Saved, and Stanton (tied for fifth) and Harper (tied for eleventh) were not too far behind. But range is not the only measure of outfield defense.

Mike Trout can cover all the ground in the world, but when he catches a fly ball, baserunners can still tag up. And they can still advance from first to third on a single if they don’t respect his arm. We measure how well an outfielder prevents runners from taking an extra base in Outfield Arms Runs Saved. That prevention can come in different forms. We include instances where an outfielder throws out a runner trying to advance, but we also include how frequently he allows runners to go first to third on a single, second to home on a single, and first to home on a double relative to other outfielders. Those plays do not often show up in the highlights, but they can have a profound impact on runs allowed.

Here were the best outfield arms in 2012:

It is fitting that the two men at the top of the list are unflashy veterans Alex Gordon and Torii Hunter. Gordon topped this same list in 2011, as well, and he was rewarded for his excellent defense in left field with a unanimous 2012 Fielding Bible Award and his second-consecutive Gold Glove. Hunter never displayed an elite arm in center field, and his overall defense began to slip there as he aged; he cost the Angels 10 runs with his defense in 2010. The Angels moved him to right field in 2011, and he has rebounded to put up 9 and 15 Runs Saved in 2011 and 2012.

A major part of that success has been his arm, which has saved his team 14 runs the last two seasons. It’s actually quite remarkable how Hunter has shown a much better arm in right field than he ever did in center. In his last five seasons in center, Hunter had a total of 10 baserunner kills (a direct throw to a base to nab a runner). His totals were three, three, two, two, and zero from 2006 through 2010. In right field, about two full seasons since moving to right in late 2010, Hunter has "killed" 26 runners on the bases.

Jeff Francoeur finished one spot behind Gordon and Hunter, but he makes a strong case as the third member of their class. The three of them were also in the top-10 in Outfield Arms Runs Saved in 2011. The rest of the list includes 2012 Fielding Bible Award runner-ups Martin Prado and Josh Reddick as well as some rising stars in Harper and Yoenis Cespedes.