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Chris Archer's breakout season continued last Wednesday against the Tigers, as the right-hander took a perfect game into the seventh inning and finished with 11 strikeouts across his seven innings of work. A trio of singles in his final inning and an error by Yoenis Cespedes ultimately led to a pair of unearned runs, which were enough for the Tigers to take the 2-1 win thanks to a performance by Justin Verlander that had Tigers fans wondering whether they had traveled back in time to 2012.

While Archer spent most of the afternoon carving up the Detroit lineup, he did get some help behind him in the sixth inning. James McCann worked a full count, and Archer went to his devastating slider on the payoff pitch. The only problem was that it caught the fat part of the plate and the Detroit catcher clobbered it to deep center field. There to make the jumping catch at the warning track, however, and preserve the perfect game was Rays center fielder Kevin Kiermaier.

Rays fans have become accustomed to plays like this by Kiermaier, whose calling card has been his speed and glove even dating back to his minor-league days. He didn't have traction in prospect circles during his time in the lower minors partly due to his late-round draft status and because of the concern that opposing pitchers would be able to knock the bat out of his hands at the highest level. But he gained helium with a strong 2013 season and was tabbed the no. 8 prospect in the Rays' system by Jason Parks in December 2013. A few months later, the BP Prospect team touted him as the top outfield glove in the minors, edging out Jackie Bradley Jr. and Albert Almora for the honor at the time.

Sure enough, Kiermaier lived up to the scouting reports in his rookie season. With Desmond Jennings patrolling center field in Tampa Bay, the Rays plugged Kiermaier into right, a spot where he shined in the eyes of defensive metrics. He trailed only Jason Heyward among right fielders in both Defensive Runs Saved (DRS) and Ultimate Zone Rating (UZR) despite not being called up for good until the end of May and playing only 68 games. After Jennings went down with a knee injury in late August, Kiermaier shifted over to center and impressed enough at the position that he got the nod as the starter on Opening Day in 2015.

Kiermaier has spent nearly all of his time in center for Tampa Bay this season—even when Jennings has been healthy—and the metrics have been even more impressed with his defense. Not only do DRS and UZR consider him the best defensive outfielder in baseball this season, they also rate him as the best defender among all players this season. It's not particularly close.







Kevin Kiermaier






Andrelton Simmons






Nolan Arenado






Lorenzo Cain






Nick Ahmed






Kiermaier stood out last season even when the metrics were evaluating him relative to other right fielders, many of whom were starters because of their bats rather than their defensive prowess. This season he's jumped to the top of the leaderboards and that's while being measured against other center fielders, many of who get their value from their gloves.

Even after taking into consideration the limits of evaluating defensive metrics over a single season, it's hard to deny that Kiermaier has emerged as one of the top defenders in the game. The scouting reports predicted it; to this point the metrics have confirmed it; and his affinity for highlight-reel catches grab even the casual fan's attention.

But is there something to the idea that Kiermaier has gotten better in his sophomore campaign? We're dealing with two small samples as far as defensive metrics are concerned, so usually you would hesitate to definitively say that he's become a better true-talent defender. But it does appear that he has been doing something differently this season. Here's a look at Kiermaier's plays made above average over the past two seasons, split up by batted-ball depth, as measured by Baseball Info Solutions. (Data through Sunday's games.)

Plays Above Average by batted ball depth, 2014-15



















After a well-balanced distribution of plays made based on depth last year, Kiermaier's plays saved on deep balls has increased significantly at the expense of shallow balls. The natural hypothesis is that perhaps Kiermaier is playing deeper this season. I looked through some games from the end of last season—when Kiermaier had moved to center field—and compared them to games this season to see if that was indeed the case.

Both of the clips above are of Xander Bogaerts batting against Jake Odorizzi with a full count, no outs and nobody on base in the third inning. I want to point out that the zoom on the shots by the two broadcasts are different and offer a slight visual bias, as you can see if you compare the heights of the outfield wall in the two clips. But if you focus on Kiermaier's position relative to either the warning track or the logo in center field, he does appear to be playing about 10 feet farther back in the 2015 clip compared to the 2014 clip.

Here's another comparison between games from last September and this July, both with Brian McCann hitting, Chris Archer pitching, and nobody on. Unlike the previous example, the broadcasts give us identical overhead shots of the field during the at bat. Here are the two screenshots, overlaid, with the more transparent players from the 2015 game.

Zoomed in:

Again, it looks like Kiermaier is playing somewhere in the ballpark of 10 feet deeper this year compared to where he was in 2014. Playing deeper in the outfield has resulted in some tradeoffs, as Kiermaier has made nine more plays above average this season on deep balls but at the expense of eight fewer plays above average on shallow balls. But deep balls are more likely to fall for extra-base hits and shallow balls tend to result in singles, so even though Kiermaier has actually made the same number of plays above average this season, he's being rewarded by the metrics for making more plays with high run values.

Going back on balls over your head is hard, much harder than coming in on a ball in front of you. As phenomenal a defender as Kiermaier is, he does get turned around on occasion and doesn't always take the most efficient routes. The play he made to preserve Archer's perfect game on Wednesday was measured by Statcast, which gave him a route efficiency of 93 percent.

He took a bit of a circular route to get to the ball, which resulted in having to reach back over his body mid-jump in order to make the catch. That route efficiency isn't as high as you'll typically see on highlight-reel plays that get the Statcast treatment, but it's not bad by any means. It was surely better than the route efficiency on these catches from last season on balls over Kiermaier's head that he made look harder than they needed to be.

Credit Kiermaier for his athleticism and ability to adjust mid-flight but it's his plus-plus speed and quick first steps that ultimately allow him to run down so many balls. It's that combination of defensive attributes that makes Kiermaier the perfect fit to play a deep center field. Adjusting mid-flight on a ball slicing one way or another is especially difficult when the ball is going over your head and it's harder to reach top speed when your head is on a swivel trying to track the ball. Compare those mid-flight adjustments to this one that Kiermaier made coming in on a ball hit by Albert Pujols in June.

Kiermaier initially judges the ball to be hit farther than it actually was, but he's able to redirect his path while running in and ultimately makes the diving play. That's a much easier adjustment to make with the ball in front of you than if you have to switch the shoulder you're looking over while you're tracking the ball.

It also helps that Kiermaier has a strong enough arm to allow him to play deeper than the typical center fielder. He was lauded for having a plus arm coming up through the minors and his throwing graded out as about average by the metrics in right field last season. Move him over to center field and his arm really stands out; he has approximately three Outfield Arm Runs Saved this season, according to BIS, and has allowed just 46 percent of runners to take an extra base. The league-average advancement rate against center fielders since the start of 2014 is 55 percent.

Basically, when you can do things like this

runners tend not to test your arm, which helps minimize another trade-off that must have been factored into the decision to have Kiermaier to play deeper this season.

We've seen evidence that teams like the Astros are using analytics to optimally position their outfielders just as it has become common to see drastic defensive shifts in the infield. With the increased amount of data at the disposal of teams, it's becoming more usual for outfielders to get specific positioning assignments against each hitter. Last month, during a FOX broadcast of a Red Sox-Yankees game, Harold Reynolds pointed out that Yankees center fielder Jacoby Ellsbury was looking into his hat prior to every at bat to see where the scouting reports indicated he should be positioned.

We know that the Rays are an analytics-inclined team, and there has to be some sound communication between the front office and the coaching staff in order to implement strategies like pulling starting pitchers out of games based on the times-through-the-order penalty. The potential benefits of having Kiermaier playing deeper this season seems like the type of thing a coaching staff and a front office would benefit from coordinating on. Maybe the analytics suggested Kiermaier would gain from consistently playing deeper; maybe the coaching staff first recognized that he was having some trouble with balls hit over his head. Regardless of who picked up on it first, I think it's pretty likely that coordination between the two sides played a role in its implementation.

Either way, this is just another example of how players are being positioned more optimally on defense than ever before. When the player in question has the defensive skills that Kiermaier does, and you put him in an even better position to succeed, that's how you end up with a player who is lapping the field this season in defensive value added.

Thanks to Scott Spratt and Joe Rosales of Baseball Info Solutions for research assistance.

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Terrific article
That overlay image (with McCann batting) is fantastic.
Love this
This was a fantastic read, and great job with the GIFs and videos too!
Thanks for the kind words, everybody. Very much appreciated!