Monday, 25 August 2014

Thinking About Garbage Numbers

On Saturday night, I saw Jarred Cosart's tweet about Adeiny Hechavarria and his fielding metrics. Fielding numbers have been controversial for most of the history of sabermetrics, so anyone with any sense to begin with should regard them as 'informed opinions'. (I also hold the view that this is somewhat true of park factors, pitching numbers and even hitting numbers, albeit to lesser degrees as one advances along that list.) Inspired by Jarred Cosart, I went to check the garbage dump at FanGraphs, and this morning my thunder was stolen, somewhat, by Jeff Sullivan's post on the matter.

What Sullivan didn't look at, but what I did look at straightaway on Saturday night, was the lesser-known 'Inside Edge' numbers at FanGraphs. 'Inside Edge' is assembled by scouts who assign a difficulty value to plays. Read more here, and Inside Edge's website is here. I found Inside Edge interesting in thinking about Miguel Cabrera's fielding during 2013, in that it suggested Cabrera did extremely well with routine plays at third base, but was somewhat taxed the more he had to move. That fit my own impression better than some awful number spat out by UZR or DRS.

This link to 2014's qualified shortstops table of Inside Edge data is sortable, if you click on the column tops. What you will see is that Adeiny Hechavarria is about average at making routine plays (those Inside Edge rates as being 60% 'field-able' or more), but slumps down the list at plays I would call 'marginal' (40-60% 'field-ability'). Looking at 'difficult' plays (40% or less), however, Hechavarria puts in his best performance. Now, if you look at FanGraphs rating of his UZR or DRS in more detail, what you'll see is that he's below average in range and in turning the double play. If he can get to a ball, he's unlikely to make an error, but he doesn't get to all the balls that he could. We see this also borne out by the Inside Edge data I described above, in that he performs badly at what I called 'marginal' plays.

There's a sense that both sides of this argument are right, which is not really the way for a humble blogger like me to get attention and land a high-paying job in the industry. Hechavarria is very good at making plays most shortstops cannot, which will often occur at critical moments in a game, and good enough at making the routine plays. But he doesn't fill the space in between too well.

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