Fielding in Prospect Analysis
A reader recently commented that people like yours truly don't talk enough about defense when analyzing prospects. I think this is a fair point, so let's take some time and think about fielding.
The traditional Five Tools of a baseball player are hitting, hitting for power, speed, fielding, and arm strength. Note that "fielding" is an aggregate category. Many of you are familiar with what I call the "Seven Skills," which is my attempt to shift the paradigm slightly. You can have a tool, but if you don't have the skill to use it, it doesn't do much good. I will write more about the Seven Skills this winter, but for today I want to focus on the fielding side.
In the Seven Skill approach, I split the generic "fielding" of the Five Tools into two seperate skills: fielding range, and fielding reliability.
Historically, baseball statistics don't deal with defense very well. The traditional stat of fielding percentage is a fair measure of reliability. But until recently, there was no way to really measure fielding range. This is a major handicap for objective prospect analysts, since fielding range is a better predictor of future defensive value than fielding reliability. It's common sense. The fielder who seldom commits errors but has limited range is unlikely to improve his range as he gets older. But the fielder who makes tons of errors but has terrific range is more likely to improve his reliability as he gains experience.
But measuring range using numbers is problematic. How do you untangle the fielder's range from all the other influences on the field? Is the pitcher a ground ball pitcher or a fly ball guy? Do the other players on the team have really good range and cut down on what the guy you are studying gets to? Or do the other fielders have poor range, enabling your guy to get more chances than he would on other teams? What about the condition of the playing field? Some parks have faster turf/grass than others. All these factors can have a big impact on the numbers.
These problems make stats like range factor too dependent on team context to be fully useful. Zone rating works better, but zone ratings are not available for minor league players. There are more sophisticated metrics that try and untangle all these influences (fielding win shares for example, or the work done by the brilliant folks at Baseball Prospectus) and some of them seem to succeed quite well, insofar as I understand them. But until very recently, most of this analysis was incomplete or unavailable for minor league players. That is changing, but there is more work to do.
In any event, fielding is something that we probably don't pay enough attention to when we look at prospects. Traditionalists sometimes overvalue defense. . .whenever bonehead TV announcers says something stupid like "Derek Jeter saves the Yankees 100 runs a year" I cringe. But just because traditionalists overvalue the glove, that's no excuse for us to undervalue the leather.
Sometimes it's easy to ignore the topic or dismiss it as not that important, but that's a mistake too, and one I will try hard to avoid in the future in my own analysis.