Fielding in the NYPL

Fielding is hard to evaluate.

It is nearly impossible to judge defense without some level of subjectivity. Even the simplest defensive statistic, fielding percentage, relies on a scorer’s decision regarding whether a play would have been made with reasonable effort. More advanced statistics such as UZR attempt to take subjectivity out of the equation by comparing each hit with similar balls, and seeing how many fielders made those plays – but (to my knowledge) it makes other assumptions that are not always true, such as assuming that fielders begin from the same position and assuming that the batted-ball classification data is necessarily accurate.

While analysts have made tremendous improvement over the past five years or so, measuring individual defense remains an inexact science. It is even more so at the lower levels, where we don’t have nearly the data that MLB teams and fans have access to. Fans looking for information on a player’s fielding are limited to their own observation and fielding percentage, which at best paints a very crude picture and basically ignores a player’s range and ability to make difficult plays.

Fortunately, measuring team fielding is easier. In its simplest form, what is fielding about? It is about making plays: turning batted balls into outs.

That’s overly simplistic, and doesn’t account for many variables – double plays, stolen bases, preventing extra-base hits, passed balls and runners taking extra bases, to name a handful. But I think most would agree that the most important job of the fielders as a unit is to turn a batted ball into an out. And that characteristic is pretty easy to measure.

Strikeouts and walks are exclusively pitching stats – the fielders have essentially no say in whether or not those occur. (You could argue that a catcher’s ability to frame pitches could occasionally make the difference in those stats, but that’s a very, very weak effect at best.) Same with home runs – plays like this one aside, the fielders can usually only turn and watch as the ball goes over the fence.

But the balls hit in play? The defense has plenty of control over those. In theory, a perfect defense with lightning-fast players could turn every ball in play into an out. The worst possible defense could also never record an out on fair balls, never moving and dropping balls right at them. Actual teams, obviously, lie far from these extremes. Good-fielding teams will turn more balls into outs than poor ones, and we can measure this.

The statistic I just described is Defensive Efficiency Rating (DER), and if you’re already familiar with it, you skimmed through the last few paragraphs because you knew all that already. The formula is:

DER = 1 – ((H + Reach on Error – HR) / (PA – BB – SO – HBP – HR))

One caveat: MiLB does not keep data for “reach on error”. The only statistic available is total errors, which includes botched pickoff throws, throwing errors from the outfield, throwing errors on the back end of double plays and other plays that solely advance runners and don’t put runners on base. I estimated the number of errors that put an opposing batter on base as two-thirds of total errors (ROE = 2/3 * E).

So, which teams are best at converting balls in play into outs?


Despite the league’s fourth-best fielding percentage, the ValleyCats best only two other teams in defensive efficiency. This is what I expected when I started this – opposing hitters post good batting averages off Tri-City pitchers despite striking out often. Oscar Figueroa has great range when he plays short but neither Healey nor Orloff are anything to write home about in that respect – both are good defensively, but more for their hands than their range. Kik&eacute has good range at second, especially to his left, but the ValleyCats have been breaking in a bunch of new players at third (Kvasnicka, Orloff, Figueroa), who don’t read balls as well off the bat yet. Adamson and Infante have great speed in the outfield, but the latter didn’t make good reads in center (a problem I’ve seen much less of since he moved back to left).

It’s important to keep these ratings in mind when evaluating pitchers – a ValleyCats hurler will see one fewer ball of 20 in play turned into an out than one on Williamsport.* The CrossCutters are 31-19 atop the Pinckney Division, in no small part because of arguably the league’s best defense. Williamsport comes to Troy tomorrow for a three-game series.

*Implied in that sentence was that getting outs in play is the full responsibility of the fielders. This is not a discussion I really want to fully get into here, but for those who might be unfamiliar with it: in the past decade of so, it has been generally accepted that major-league pitchers have little control over what happens to a ball in play. (An exception is that knuckleballers, submarine pitchers and other unconventional throwers usually allow fewer hits than standard pitchers.) Note that this has not been shown to be true or untrue at the minor-league level.

Kevin Whitaker

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