Judging Defense

It's still early in the season but after 15 games - depending on what numbers you use and how you judge the overall effectiveness - we just might have the second best defense in the NL so far.  Yes, this sounds a little crazy if you know the players as well as we do by their reputation, but the numbers don't lie ... do they?

Starting with the numbers.  Admittedly using a small sample - only 15 games into the season - the Brewers are #1 in fielding percentage.  This is a stat that is not very well received in the analysis community right now because like RBIs - stats that depend on opportunity - errors only occur when you actually reach the ball and misplay it or make an errant throw, they do not take into account how much of the field the players cover and whether a ball hit up the middle that could have been reached by most players was waved on into center field by a middle infielder with poor range.  Nevertheless, the Brewers have committed only 5 errors in 550 chances, for a fielding percentage of .991.

So what that stat tells us is that if the Brewer fielders make a play on the ball, they are making fewer mistakes than any other team in the NL.  This is good.  But, how many plays are they making?  Well, you can only make a play on balls in play, and the Brewers are #2 in the NL in turning balls in play into outs.  They've converted 70.8% of balls in play to outs, a rate beaten only by the Florida Marlins.

So at face value it looks like our defense is pretty hot stuff, right?  Our total zone fielding runs above average is 11, which means we're saving almost 2/3 of a run per game from our defense alone.  Is this really possible?  We've got the Adventures of Braun in LF, gritty Kotsay in RF, cat-like reflexes at 1B, McRegression at 3B, and E-6 at shortstop - we were supposed to be a questionable defensive team this year.  Aside from CF (and the C stands for CARLOS), I thought defense was supposed to be our weakness this year?

Unless FieldF/X shows up to save the day, I don't think we'll know the whole truth.  It's possible that the addition of Marcum, an improved Narveson, and Kameron Loe's sinker are forcing more ground balls.  The pitching staff as a whole could be placing pitches better for more playable balls, and the coaches might be positioning fielders better, giving them safe chances.  It might just be early. 

And I think this is exactly why people are drooling over the data that FieldF/X would provide.  But it's possible the stats community might not get their hands on the numbers, and they might be kept exclusively by MLB teams:

If [Red Sox baseball information services director Tom] Tippett has any say in the matter, clubs will keep data to themselves.  "I want this to be adopted by Major League Baseball, made available to all the clubs, but kept within the industry," he says.  Tippett admits that broad access to PitchF/X data produced useful ideas and that as a fan he values open access, but he knows who signs the checks.  "We don't get paid to advance the state of the art in analysis," he says, "We get paid to put a winning team on the field."

Add into the equation that the sheer bulk of data being recorded by FieldF/X - 2 Terabytes of data per game - and the community might be limited as to how much it can analyze and contribute to the inventive process of turning data into actionable information.  And until we have more conclusive information to work with I'm left to wonder, is our defense as good as it looks or as bad as we thought but hiding behind pretty numbers?


Am I reading the stats right?  Got theories?  Please comment :)

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