From SABR member John Dewan at ACTA sports on January 6, 2012:
Defense in the outfield isn’t just about how well you track flyballs. Once an outfielder has the ball way out there in the pasture, he has to get it back in to keep baserunners from advancing. It’s not just about throwing out baserunners and earning assists. Preventing a runner from advancing from first to third on a single and holding the lead runner at second base, and other situations like this, are important aspects as well. These are skills that we at Baseball Info Solutions quantify with our Outfield Arms Runs Saved metric.
Outfield Arms Runs Saved is a measure of how well an outfielder prevents baserunners from taking the extra base. It is one of the components of Defensive Runs Saved that measure overall defense for every player. The most common opportunities outfielders have for saving extra bases is in preventing runners from going from first to third on a single, second to home on a single, or first to home on a double. In each of these situations we look at how often the baserunner took the extra base, how often the baserunner moved up just from station to station, and how often the baserunner was thrown out trying to take the extra base. We then also consider any other instance where an outfielder throws a runner out – e.g. if he throws out the batter, or if he throws out a runner trying to advance on an out – to get a full measure of how effective his throwing arm is.
We have recently been working on some enhancements to our methodology for The Fielding Bible—Volume III. Now we are taking into account many more variables to determine how an outfielder should be expected to prevent the extra base on any given opportunity. For example, we now factor in such things as the number of outs, the location of the hit, the hang time and the velocity of the batted ball to determine how difficult each play is for the outfielder to prevent runner advancement.
Read the full article here: http://www.actasports.com/statoftheweek
Originally published: January 6, 2012. Last Updated: January 6, 2012.