Testing Outfield Arms
Over at The Hardball Times, John Walsh used to write one of my favorite pieces of the year; a ranking of the game's best outfield arms. Walsh would find every outfielder's "kill" and "hold" rates in five distinct situations. Walsh has taken a hiatus from the exercise this year, so I'd like to pick up on the research, adding Gameday's hit location data to the mix.
Walsh has already covered 2008, yet I've chosen to use both 2008 and 2009 data in my study. The hit location coordinates provided by Gameday make it difficult to decipher the exact distance of a ball to the outfield. But the batted ball angle relative to home plate can be calculated. Fortunately, Walsh outlined two parameters in which distance is more or less immaterial, and only the angle matters.
1. Single with runner on first base (second base unoccupied).
2. Single with runner on second base.
All singles land somewhere in front of the outfielder. And it turns out, the success of the base runner depends little on whether the outfield single was a grounder, a line drive, or a fly ball.
Excluding all two-out plays, I found the rates at which base runners advanced or were thrown out attempting to advance, depending on the batted ball angle.
On singles directly at the left fielder, base runners attempt to advance first to third only 5% of the time. Right at the center fielder, base runners risk it 15% of the time, and 25% of the time on balls to the right fielder. 40% in the left-center gap and 60% in the right-center gap. These figures coincide with how often balls are hit to each location, meaning that outfielders align themselves sensibly. What doesn't make sense is that runners are thrown out trying to advance on balls to center as often as they're thrown out trying to advance on balls to right. Sure, right fielders have better arms than center fielders, but center fielders are closer to third base and get to the ball faster. I don't know what the numbers should look like if base runners advanced optimally, but I do know that the rate at which runners attempt to advance should be directly proportionate to the the rate at which runners are thrown out attempting to advance.
That theorem holds when base runners on second try to score on singles.
Singles targeted at corner outfielders are 50-50 plays for the third-base coach/base runner, and that risk/reward proposition can fluctuate depending on the number of outs, the upcoming batter, the current pitcher, and all that stuff. Center fielders, who are positioned farther from the plate and have to circumvent the pitcher's mound with their throws, are tested at a 75% rate. There is a higher frequency of singles to center, specifically of the ground ball variety, with a man on second than with a man on first due to the infield alignment.
I compared the expected rates to what actually happened to evaluate base runners and outfield arms. So if a runner advanced first to third on a ball right at the right fielder, they would both accumulate .75 extra bases and -.05 extra outs.
Here are my top five and bottom five base runners at advancing on singles.
The Angels are a very aggressive base running team, which pays off with guys like Figgins and Aybar. Matt Kemp's fielding and base running production have taken significant, almost shocking, hits this year. Jorge Posada is the worst base runner I've ever seen, and he's probably one of the worst of all-time. Considering his defense, which has never drawn positive reviews either, his Hall of Fame case will be very interesting.
To evaluate outfield arms, I included a regressed version of these base running scores.
Baseball Reference actually carries these stats. Hunter Pence, a right fielder, was tried 100 times on singles with a man on second. He held the runner at third 40 times, leaving 60 tries for him to nail the runner. He succeeded on ten, which is quite an impressive rate. All three of the Phillies outfielders have been successful holding the running game. Bourn was also an above average base runner, and Ichiro, renowned for his arm and base running, was merely good in each. Shin-Soo Choo is the biggest surprise I found, as I've heard that he has "80" arm strength before.
And the rest: