What Jhonny Peralta Tells Us About Defensive Metrics

Five years ago, the Cleveland Indians decided that Jhonny Peralta just wasn’t capable of playing shortstop at the Major League level anymore, shifting him to third base to allow Asdrubal Cabrera to move back from second base to shortstop, the position he had primarily played in the minors. Peralta had never put up particularly good defensive numbers at shortstop, and with a thick lower half, he certainly looked more like a third baseman than a middle infielder.

After roughly a year at third base, while still hitting like a shortstop, Peralta was traded to Detroit. The Indians weren’t going to pick up his $7 million option for 2011, and the Tigers were looking for an infielder to give them some depth on the left side of the infield. Peralta played third base for a week with the Tigers, but then incumbent Brandon Inge returned from the disabled list, and the Tigers moved Peralta back to shortstop.

Since that move, Peralta has played the position exclusively, spending four years at shortstop between Detroit and St. Louis. And along the way, a funny thing happened; UZR fell in love with Jhonny Peralta’s defense.

Over the first 6,000 innings of Peralta’s career at the position, UZR had rated him as a -28 defender, or -6 runs per 150 games. He was decidedly below average, even though he was very good at error avoidance (+8 runs) and turning double plays (+5 runs). Peralta’s lack of range (-41 runs) was a legitimate problem, though, and what got him moved off shortstop to begin with.

In 2010, in his first full year back at shortstop, UZR rated Peralta as an average defensive shortstop. In 2011, that jumped to +10, putting him in the same range as defensive specialists Brendan Ryan and Alexei Ramirez. It was, at this point, that Peralta became something of a poster boy for the flaws of defensive metrics. After all, everyone knew that Peralta was actually not a good defender. The Indians had already moved him off the position. He had no range. Ranking Peralta as an elite defensive shortstop was evidence that UZR was not to be trusted.

Instead of regressing back to his prior mean in 2012, however, his UZR actually got even better, going up to +11.5, and again ranking third best among Major League shortstops. Among others, he rated ahead of Clint Barmes, Brandon Crawford, and Elvis Andrus, each of whom were essentially in the big leagues because of their defensive abilities. Again, the rating was seen as evidence that UZR wasn’t reliable, and Peralta was held up as an example of the system’s limitations. Perhaps playing next to Miguel Cabrera was throwing the system off, giving him credit for making plays that a better third baseman would have gotten to instead.

In 2013, Peralta’s UZR finally did regress some, though the system still thought he was an above average defender, putting him at +5 runs per 150 games. However, a 50 game suspension for his ties to Biogenesis led to the Tigers trading for Jose Iglesias, essentially ending his career as the Tigers shortstop; when he returned for the postseason, they experimented with using him in left field, because no one in their right mind would choose Peralta over Iglesias at shortstop, even though UZR was on year three of ranking Peralta as one of the better defenders in the game at the position.

With Iglesias in the fold, the Tigers bid adieu to Peralta this winter, not even making him a qualifying offer that could have returned a draft pick as compensation for letting him leave. With a poor defensive reputation and the Biogenesis connection hanging over his head, there were low expectations for what the market would offer him; MLBTradeRumors guessed 3/$30M, Jim Bowden guessed 2/$20M, and Jon Heyman guessed 2/$16M, with an agent and GM polled in that same piece only coming in slightly higher. Everyone basically agreed that he’d get something like $10 million a year for two or maybe three years.

Instead, the Cardinals gave him $53 million over four years. The Cardinals, one of baseball’s most respected organizations, bet big on Peralta’s ability to play shortstop. If he was actually a below average defender, or was going to need to move to another position in a couple of years, the deal would have been a ridiculous overpay. The only way to justify that price for Peralta is to argue that the defensive metrics were correct and that the public perception of Peralta’s defensive value was wrong.

So, fast forward to 2014. Peralta is no longer playing next to Cabrera, but is instead lined up besides one of the better defensive third baseman in baseball. He’s no longer playing behind the Tigers dominant pitching staff and weak-contact generators like in-his-prime Justin Verlander. He’s changed leagues, parks, and teammates, and yet again, he’s rated as the third best shortstop in baseball by UZR, second best if you use UZR/150.

Yes, Jhonny Peralta is rated higher by UZR this season than defensive wizard Andrelton Simmons. And that little factoid is an endless source of entertainment for people who want to again remind you to not put too much trust in defensive metrics. After all, no one actually believes that Peralta is a better defender than Simmons, so a result like this makes it easy to question the entire system.

Only the arguments for Peralta actually being a bad defensive shortstop are getting harder and harder to find.

Small sample size? Well, not anymore. We’re now on year four of Peralta being rated as an excellent defensive shortstop by UZR. Since the start of the 2010 season, he’s played over 4,600 innings at the position, and he has a UZR/150 of +10 runs per season over that stretch. Over the entirety of his career, spanning nearly 11,000 innings at shortstop, he’s rated as slightly above average. While defensive metrics absolutely do need larger sample sizes than offensive metrics, Peralta is well out of range of the small sample arguments.

The Cabrera factor? Well, UZR first rated him well while Cabrera was still playing first base, and his rating actually didn’t change much in the first year where he played next to a third baseman who could barely move. And now that he’s playing next to a much better defender, his defensive numbers have actually improved. There’s no real evidence for the idea that playing next to Cabrera artificially inflated Peralta’s defensive numbers.

The Tigers’ pitching staff? Well, nine players have played shortstop for the Tigers since the start of the 2010 season, and of those nine, only two of them have posted better defensive numbers than Peralta. That includes a few months of time from Jose Iglesias, who passes every eye test for elite defensive ability, and yet graded out slightly worse during his few months behind the Tigers pitchers than Peralta did during his tenure at the position. And playing behind a Cardinals pitching staff that has been decimated by injuries, resulting in a carousel of ever-changing arms who do not specialize in weak-contact, has not caused Peralta’s ratings to fall.

Peralta may or not be as much of a defensive asset as UZR claims; the model is still an educated guess, essentially, and it can certainly get things wrong. But the evidence is really starting to stack up against the Peralta-is-a-bad-defender idea. Even if you don’t buy into UZR at all, and you think that more granular measures that incorporate things like batted ball speed and launch angle would prove that UZR was overrating him, then you still have to explain how the Cardinals — one of the most aggressive teams in collecting and analyzing that kind of data — were willing to dramatically outbid the expected price for him as a free agent.

To believe that Jhonny Peralta is a poor defensive shortstop, you have to think that UZR is not just limited in value in smaller samples but completely useless regardless of the amount of data it has, while simultaneously believing that the Cardinals either don’t know how to evaluate defense or don’t know how to properly value free agents. Good luck defending those ideas against the mountains of evidence to the contrary.

So often, defensive data is assailed for not matching what the eye test leads us to believe. Peralta has been the poster boy for this disconnect, but at this point, there’s more evidence that the data was right and the eye test was wrong than vice versa. That doesn’t mean that the data will always be right whenever there’s a disconnect, or that we should just put full faith into single season defensive numbers, but perhaps Peralta can be a reminder that the eye test might be just as flawed as the metrics. There’s nothing wrong with being skeptical of defensive statistics; you should also be skeptical of things that are obviously true even when the data asserts otherwise, however.

UZR is imperfect. It will get things wrong. It might even still be getting Jhonny Peralta wrong, though that’s getting less likely by the day. But Jhonny Peralta should no longer be considered the poster boy for why UZR is unreliable. If anything, he should perhaps be the poster child for why we shouldn’t put unfailing trust in our own abilities to evaluate a player’s defensive value by watching him play.