Tampa Bay Rays center fielder Kevin Kiermaier might be having the best defensive season we know of

Just in case, let’s get this out of the way early: Kevin Kiermaier is the Rays’ center fielder. You probably already knew that, but you can never be too safe. Kiermaier is considered by everyone to be something of a defensive whiz. They say you’re supposed to open with a joke. Here’s a funny picture that proves even a defensive whiz can end up in a humiliating screenshot:

There’s a perfectly good explanation for what happened that relieves Kiermaier of pretty much all blame, but it’s more fun if you don’t know. Look at that guy! What a silly person.

Realistically, for the hitter, it’s probably a good thing that what happened happened. Spoiler alert: By rule, the hitter was awarded a home run. Had a physical structure not interrupted the flight of the baseball, there’s a decent chance Kevin Kiermaier would have, a few seconds later.

Major League Baseball fans were first introduced to Kiermaier late in 2013, when the Rays called him up for tiebreaker game 163 and the AL Wild Card Game. Kiermaier wasn’t promoted to serve as some sort of dangerous slugger off the bench. Nor was he around to be a potential pinch runner. Kiermaier was brought up specifically for his outfield defense. The Rays knew it was a little crazy, but they thought Kiermaier was the best defensive outfielder in the organization, so it wasn’t hard to talk themselves into it. Kiermaier played an inning in the first game. He played two in the second. That was it. Over the winter, Baseball America called Kiermaier the No. 10 prospect in the system

Some prospects go away. Some hype proves to be unjustified. I don’t think it would’ve been a shock had Kiermaier never shown up again or had he been limited to a bench role. But he wound up playing 108 games last year as a rookie, and he’s already close to 130 as a sophomore. Kiermaier’s bat has developed enough for him to play nearly every day. And because he’s played so often, we’ve seen ample evidence of his defensive skill. The Rays, back then, were on to something. I’m obligated to share some defensive highlights. The hardest thing is picking. Here’s a highlight

Wonderful! Here’s a highlight:

Pretty great! Here’s another highlight:

Outstanding! Based on anecdotal evidence, Kiermaier’s a hell of a center fielder. We can also do a little better than anecdotal evidence.

Maybe soon we’ll be able to pull some really interesting information from Statcast. Maybe it’s going to be our solution to wanting to understand defense a little better. We don’t have that much yet, but I can at least offer this simple tweet from not long ago:

OK, that’s curious, but still sufficiently unfamiliar that one shouldn’t make too much of it. You can envision a guy covering a lot of ground to make a routine catch. So let’s look at some defensive metrics. I know the term "defensive metrics" makes some people automatically roll their eyes, and that’s perfectly fine. But while the numbers could be improved, they’re the best we have. They’re not measuring nothing. So we should take them into consideration.

FanGraphs offers two numbers in particular — Defensive Runs Saved (DRS) and Ultimate Zone Rating (UZR). The units for both are runs above or below average at the given position. The stats are different because the equations are different, but the general idea is to compare plays made and not made to how often similar plays are made on average. If a player makes more plays than you’d expect, he’d get a positive rating. Fewer plays, negative rating. It’s pretty intuitive. Allow me to repeat: The numbers aren’t perfect, or even all that close to it, but they’re also far from worthless, especially when DRS and UZR agree with one another. Let’s get to some measurements.

DRS is available going back to 2003. UZR is available going back to 2002. For these purposes, we’re going to ignore catchers, who are defensively unique. First, the best seasons on record in terms of DRS per 1,000 innings:

  • Kevin Kiermaier, 2015, CF, +38 runs per 1,000 innings
  • Gerardo Parra, 2013, RF, +35
  • Juan Lagares, 2013, CF, +32
  • Carlos Gomez, 2013, CF, +31
  • Jack Wilson, 2009, SS, +31

Interesting. Now, the best seasons on record in terms of UZR per 1,000 innings:

  • Alfonso Soriano, 2007, LF, +30 runs per 1,000 innings
  • Brett Gardner, 2010, LF, +28
  • Shane Victorino, 2013, RF, +27
  • Franklin Gutierrez, 2008, RF, +27
  • Juan Uribe, 2013, 3B, +27
  • Kevin Kiermaier, 2015, CF, +26
  • Juan Lagares, 2013, CF, +26
  • Gerardo Parra, 2013, RF, +26

By one, Kiermaier’s at the top. By the other, he’s near the top. It’s not entirely clear which measure is the better measure, so one compromise: Just take the average of the two. So, combined, here are the best seasons on record:

  • Kevin Kiermaier, 2015, CF, +32 runs per 1,000 innings
  • Gerardo Parra, 2013, RF, +30
  • Juan Lagares, 2013, CF, +29
  • Franklin Gutierrez, 2008, RF, +29
  • Brett Gardner, 2010, LF, +29

Kiermaier slots in at No. 1. Now, importantly, Kiermaier’s season isn’t over yet. He’s got another month, and it’s hard to sustain such a level of performance. Also, importantly, it can’t be overstated that we don’t understand defense like we understand offense. A lot of it is sort of guessing. Every number comes with error bars, but that’s why this post’s headline is the headline. Something might not be true, but it appears that it might be true.

Oh, and I should note — position is important. Kiermaier plays a premium outfield position. In the list above, Gerardo Parra is in second, but Parra was in an outfield corner, so his defensive performance means less than, say, Juan Lagares’ right below. Lagares is a good comp here, in that he plays the same premium position as Kiermaier. And like a healthy version of Lagares, Kiermaier derives a decent amount of his value from his throwing arm. This year, he already has 13 assists. Defensively speaking, there’s nothing he can’t do. And he can do enough at the plate to look like a borderline star player despite roughly average offensive production.

When you take position into consideration, Kiermaier’s up there with Lagares, Carlos Gomez and Andrelton Simmons. Prime Jack Wilson. Prime Adam Everett. There’s no conclusive way to know, but this much is fair: Right now, Kevin Kiermaier might be having the best defensive season we know of. That stretches back only a little more than a decade, but that’s a lot of time, with a lot of players. Kiermaier’s outshining quite possibly all of them.

Last year, it was Lorenzo Cain who made this sexy. It’s not a fashion that goes out of style.