Is David Peralta a good defender?

While it was little or no surprise to see Nick Ahmed and Zack Greinke take home Gold Gloves when they were announced, the third Diamondback to receive one did come as a bit of a surprise. For David Peralta’s defense has never really been an area which had generally been regarded as one of his strengths. When he followed that up with the Wilson Defensive Player of the Year for left field, which honors the best player in either league, it definitely seemed something worth digging into further, spurred in part by this.

There’s no doubt that Peralta’s defense has certainly got better. But that’s no surprise, given the well-known story of how he was a pitcher initially, and only turned to the outfield after washing out of the Cardinals’ organization. Most MLB outfielders played the game from at least high-school, into college and up through the minor leagues. So by the time they reach the majors will typically have a decade or more experience under their belts already. In contrast, Peralta’s first recorded “in-game” experience was with the indie ball Rio Grande Valley Whitewings in 2011. He made his major-league debut on June 1, 2014, after barely three years as an outfielder.

And, to be frank, you could sometimes tell. Nothing highlights Peralta’s issues than the embarrassing play below, from 2017. Occupying right-field, Peralta first fell over, then when he got up, lost the ball in the sun, and it plopped to the turf a couple of feet to the right. The worst part of that might have been Peralta’s sunglasses being stashed, stylishly yet entirely uselessly, on the bill of his cap. He explained afterward, “I had my sunglasses on my head, but the sun wasn’t hitting right at me. But when I fell down and tried to look for the ball I looked straight to the sun.” Still, that’s more of an explanation than an excuse, and it wasn’t a good look for the Freight Train.

However, there’s one change which happened after that season, which may have proven key to helping Peralta reach his defensive potential. In both 2016 and 2017, he was primarily a right-fielder, making 110 starts there, compared to 48 in left. But since then, he has almost exclusively been a left-fielder, and according to outfield coach Dave McKay, having a consistent spot seems to have helped. There was also a tweak in the way Peralta set up before the pitch, pointing more towards second-base. Said McKay, “It’s an adjustment that really helped him. He’s getting more comfortable with it and it’s more of an instinctual thing instead of having to think, think, think.”

It’s particularly interesting to see the apparent development in his performance over time. Below are the Defensive Runs Saved (DRS), as calculated by The Fielding Bible for Peralta in left, since he reached the majors in 2014:

• 2014: -2 (in 260.1 IP)
• 2015: -2 (in 982.2 IP)
• 2016: Didn’t play LF
• 2017: +3
• 2018: +5
• 2019: +10

That’s a consistent, and dramatic, improvement over a five-year period. Pro-rated, say, to 1,050 innings, that 2014 figure would have made Peralta the worst left-fielder in the majors. Fast forward to 2019, and no left-fielder saved more runs than David. Other metrics seem to support this. Total Zone’s Fielding Runs Above Average (FRAA) and Baseball Info Solutions’ DRS both have Peralta top in the National League, at +11 and +10. It helps that even with all the time he missed, David was still among the top five for innings played at the position, which helps rack up counting stats like these. But it’s clear that Peralta has put in a lot of work to improve his defense, and that has paid off.

Below, is a video of some of his defensive highlights - it says 2019, but a few are actually from last year. No big matter. :)

The praise is not unanimous, however. The StatCast metrics do not see Peralta as a particularly good outfielder. Using the figures for catch probability, it’s possible to work out how many outs above average a player recorded. For example, a fielder who catches a 25% Catch Probability play gets +.75; one who fails to make the play gets -.25. Sum that over the course of a season, and Peralta sits just inside the top fifty of qualifying players, at a mere +1. He was expected to catch 86% of the balls and caught... 86%. In particular, these number show him weak at balls hit back and to the left, towards the Diamondbacks bullpen, where he rated -3.

What we also see from these numbers is Peralta’s inability to make great catches. That’s something I noticed when looking through video for Play of the Year nominees. He made some good ones, but there was little or nothing which could be considered to be really outstanding. And the StatCast figures bear this out. They rate as a 5-star play, one with a catch probability of 25% or lower, and 4-star plays are those between 26-50%. Last year, David Peralta didn’t have a single play in either category, going 0-for-22 in 4- and 5-star catch opportunities, though made up for this with better reliability in the other groups. For comparison, Jarrod Dyson went 5-for-21 and Tim Locastro 3-for-14 in those 4/5-star plays.

Peralta’s jump time may be a factor in this, coming at at -0.9 with his burst speed (the portion between 1.5 and 3 seconds) the most significant component in that. The chart above plots the other two elements, burst speed and route, against each other for all qualifying players, with Peralta’s dot highlighed. You can see he’s almost exactly average in both of those, and at best, the same can be said about Peralta’s sprint speed. At 26.9 feet/second, that’s almost exactly league average (27.0) - and that average is probably higher for outfielders. Limiting it to just left-fielders, Peralta ranks 28th of 42 by sprint speed (min. 75 measurements).

So how do we explain the difference between these mediocre underlying numbers, and the glowing reports from overall metrics like DRS and FRAA? It may well be not dissimilar to the way that Paul Goldschmidt became an outstanding base-runner, despite not being the fastest guy on the team. “Field smarter, not harder,” is perhaps how you can think of it, and I suspect McKay deserves some of the credit. Tweaks like the set-up change mentioned above will help players like David to squeeze every ounce of potential out of their talent. It wouldn’t surprise me if outfield defensive shifts also help the Freight Train to look good, perhaps making some 4-star balls into 3-star chances which he can make.

This isn’t to downplay the enormous contribution of Peralta. All the advice in the world would be useless if the recipient isn’t willing to a) listen, and b) make the necessary effort to put the changes into practice. As Goldschmidt shows, being the best you can be, involves working on weaknesses. Even if you can’t necessarily turn them into strengths, you can still minimize their impact simply by bringing those aspects of your game up to average. David deserves nothing but credit for his efforts, and winning these honors is yet another chapter in one of the most remarkable stories in the history of the Diamondbacks.