If someone asked you to guess which right fielder provided the most value on the defensive side of the ball last year, the only logical answer is Jason Heyward. Heyward was so far above his compatriots that you almost wonder if he was simply not supposed to be a right fielder and that Fredi Gonzalez’s lineup card handwriting was somehow confusing the players and sending them to the wrong positions.

Heyward posted 32 defensive runs saved and a 24.1 ultimate zone rating in 1317 innings in right field. No one else was even in the ballgame, but if you had to guess who was second, it might be a little more difficult. Enter Kevin Kiermaier. Kiermaier’s 14 DRS and 16 UZR in right field landed him at second on a list of right fielders sorted by DEF, which is UZR and the positional adjustment.

DEF is a cumulative statistic, meaning more opportunities can lead to higher numbers. Heyward’s DEF was 17.3 and Kiermaier’s was 13.3, but Kiermaier played just 526.1 innings in right field last year. If you convert those marks to a rate statistic, say UZR/150, then Kiermaier rockets up to an insane 56.6 UZR/150 while Heyward settles just above 20. By the numbers, Kiermaier was the most dazzling defender we saw in right field last year.

Now, obviously you shouldn’t make too much of Kiermaier’s 500 inning sample as far as the actual numbers are concerned. No one is a +50 DEF player, save maybe for the most elite defensive catchers, and I wouldn’t even use these numbers to suggest Kiermaier is a better defender than Heyward. That isn’t the point.

But if you go back to 2003 and look at right fielders who played at least 500 innings in a season, Kiermaier’s 2014 campaign isn’t just the best by UZR/150, it’s the best by 17.2 runs. Out of the 365 player-seasons in that sample, the UZR/150 standard deviation is around 14, so it’s not surprising that we see these big outlier seasons. It’s a noisy proposition to measure defense.

But 56.6 is more than four standard deviations above the mean and that kind of thing just doesn’t happen by random chance. Kiermaier’s a good defender, which you know if you watched him, looked at the numbers, or listened to anyone who knows the game. The actual numbers are fun for how outlandish they are, but you don’t need them to get the main idea: Kiermaier’s glove is outstanding.

This year, he’s going to get a chance to play center field and if you factor in some normal regression and then try to convert his right field numbers to center field, it’s not crazy to think he could be a +10 center fielder over a full season of work. There’s a fair amount of uncertainty in estimating something like that, but I’ve heard similar reports from people in the game with access to better information.

So even if we’re extremely conservative and call him a +5 in CF, when you factor in replacement level, the positional adjustment, and a run or two of base running value, we’re talking about a 2-3 win player if he’s merely a league average hitter. Last year, we had him at 4.0 WAR in 364 PA, which is something like 6.5-7.0 WAR over a full season. Even with conservative estimates on his glove, he’s an above average player, but if you allow for him to truly excel in center and repeat what he did at the plate last year, you’re talking about a superstar player. How likely might that be?

Just a year ago, Kiermaier was 8th on Baseball Prospectus’ list of Rays prospects. Our Marc Hulet had him 13th. And the Rays farm system isn’t the star-studded cast it used to be. Everyone raved about his glove, but questioned the bat, suggesting that his upside was second-division starter thanks to that defense, but most likely he would just find time as a role player. What happened between then and now?

Kiermaier hit well in Durham and got promoted to Tampa Bay where he put his glove on display, making plenty of highlight reel catches. The defense didn’t surprise anyone, but seeing it work at the major league level certainly solidified that side of the projection next to excellent marks using DRS, UZR, RZR, and Inside Edge.

With the bat, however, Kiermaier had a terrific stretch, providing a 119 wRC+ without a high BABIP (.306). He walked a little less than average and struck out a touch less too while hitting for a nice bit of power (.187 ISO). He didn’t set the world on fire, but he had 34 extra base hits in 364 trips to the plate, which is pretty remarkable for someone who can also save as many runs as he can on defense. He hit much better against righties than lefties, but in such a small sample its hard to judge the true split, and even if he has one, it’s better to struggle against lefties than righties.

He’s aggressive on pitches in the zone, but doesn’t chase or swing and miss any more than the average player, at least he hasn’t to date. The Fan Projections love him, as they often do with breakout players, but oddly enough they expect his offense to repeat and his glove to cool off, for whatever that’s worth.

The obvious concern with Kiermaier is that he’s never showed this much power in the minors and his production at lower levels was driven by a high BABIP, indicative of a fast player hitting against lower caliber defenses. There’s plenty of room for his bat to regress, with Steamer and ZiPS splitting between 96-102 wRC+ over a full season. On the lower end of things, I’ve heard skeptics in the game suggest a 90 wRC+ is more likely.

But even if he’s 10% worse than average at the plate, his elite defense in center makes him a valuable asset to the Rays. It seems like at worst Kiermaier is a 2 WAR player and could realistically be a 4-5 WAR player if the bat is anything like what we saw last season. He had a great opening series against the Orioles, and it’s easy to miss the fact that he won’t turn 25 for two more weeks.

Defense and speed peak early, so he’s not going to be a plus infinity defender forever, but players with his kind of value on that side of the ball just need to make minor offensive strides to become really excellent players. It’s not a perfect comparison, but I actually think putting him side by side with Manny Machado is pretty interesting.

Name PA HR BB% K% ISO BABIP Manny Machado 1266 33 4.6 % 17.3 % 0.155 0.316 Kevin Kiermaier 364 10 6.3 % 19.5 % 0.187 0.306

Name AVG OBP SLG wOBA wRC+ BsR Off Def WAR Manny Machado 0.278 0.313 0.434 0.326 104 -3.2 2.1 47.5 9.8 Kevin Kiermaier 0.263 0.315 0.450 0.333 119 2.0 9.5 15.5 4.0

The sample size is obviously a limitation here and we won’t know anything definitely for another year or two, but Machado is considered one of the bright young stars of the game with a pretty similar skillset as Kiermaier, even though his prospect pedigree is a little more impressive.

At worst, the Rays have a really useful player and at best they may have a cornerstone player who hits well enough to wind up as a reduced version of the only men, Alex Gordon and Jason Heyward, who played the kind of corner defense that Kiermaier did last year.