Range is a pretty big deal these days. An outfielder’s ability to catch a batted ball before it hits the ground is the proprietary data tease of the moment and has recently become one of the most difficult and expensive skills to acquire on the open market.

But range isn’t the only means of run prevention. An outfielder’s arm also accounts for some of that value and it is easy to underestimate just how often those situations occur during the course of a baseball game. For every two balls an outfielder catches for a putout or scoops off the ground, he gets more than one opportunity* to prevent a baserunner from advancing closer to home. No outfielder gets more of these chances and opportunities than the center fielder:

This does not include throws made against a batter attempting to advance an extra base, so by definition the center fielder’s ability to impact the game with his arm accounts for an even greater percentage of his total chances. On the other hand, just because a situation is defined as an "opportunity" it is often not true in actuality. Some advances are unavoidable regardless of the outfielder while others are universally preventable. Billy Hamilton is going to score from second on a two-out single blooped in the gap regardless of who is playing center. Billy Butler is not advancing from first to third unless he is literally on fire and third base is a tub of water, or better yet gravy.

It is the gray area in between those two extremes where Leonys Martin is making history. But Martin is not making history independently. It also takes baserunners foolish enough to test his prodigious throwing arm:

There aren’t many truly unique skills in baseball, but a center fielder with an all-time great arm certainly qualifies. The Mariners have one and he appears to be the best by a ridiculous margin. Behold the ARM values of the top 10 center fielders with a minimum of 3,000 innings played since Fangraphs started tracking this data in 2002:

These are the standard ARM values on a per-play basis adjusted to the league average number of plays for a center fielder over 162 games (ARM/Yr). So far, the value of Martin’s throwing arm has outpaced the next best center fielder by 43%. Combine the 3rd and 4th ranked center fielders and they still fall short. Perhaps we shouldn’t be comparing Martin to the pool of pea-shooters who typically roam center field. Here is the same data using all outfielders:

If you ever wanted a compilation of the best throwing arms since 2002, there it is – a list full of firepower and very few surprises. If one is so inclined to dig around, Baseball-Reference gets more in depth, separating baserunner holds from kills. They do not provide a searchable list of career Advanced Fielding statistics – only by season or individual player – but I did some digging, with a list of the most legendary throwing arms in baseball history according to people who publish such things on the internet. Here is what I found:

Check out the Kill%Dif column on the far right, which is Kill% (baserunners thrown out per opportunity) above LgKill% (league average baserunners thrown out per opportunity). So far in his young career, Martin has been better at gunning down baserunners than every other legend of the outfield throw. Better even than Jesse Barfield, who is widely considered to have possessed the most valuable outfield arm of all time. Better than Ellis Valentine, who is the only outfielder in history with a higher combined Held%Dif and Kill%Dif than Barfield. Better than Roberto Clemente, Dave Parker, Raul Mondesi, Andre Dawson and likely any other outfielder one can name. I didn’t check them all.

Barfield and the others had something Martin may not have yet, and that is a reputation. The more kills an outfielder makes, the more holds he gets by inspiring fear in potential base advancers – a phenomenon that happens to be one of those wonderful old-school baseball theories confirmed by statistics. When Barfield reached the 5,000-inning mark, he experienced an abrupt and sustained 6% jump in Hold% accompanied by a 1.5% drop in Kill%. It only took Valentine 3,000 innings to see a similar curtail in baserunner bravery, albeit less drastic. Jim Edmonds and Andy Van Slyke maintained a 6% increase in Hold% after 6,000 innings. The story is the same for most of the outfielders on the above list.

Considering the role scouting and statistics play in modern decision making – a heightened awareness of the value of an out carelessly sacrificed on the base paths – and the fact Martin is gunning down baserunners at an all-time great clip, it won’t be long before Martin’s arm and reputation reach equilibrium and baserunners exercise more restraint. Until that time comes, however, Leonys Martin is the ultimate kill machine.

Go M's.

*Opportunities as defined by Baseball-Reference’s Advanced Fielding metric, comprised of the five following situations: 1) Single w/ Runner on 1st; 2) Single w/ Runner on 2nd; 3) Double w/ Runner on 1st; 4) Flyout, less than 2out, Runner on 3rd; 5) Flyout, less than 2out, Runner on 2nd.