Ever since it opened in July 1999, Seattle’s Safeco Field has had a reputation as a pitcher’s park, and for good reason. (“Everyone thinks of subpar offense in Seattle because the Mariners have given nearly 1,500 plate appearances to Willie Bloomquist over more than a decade, right?” That’s not the right answer, but it certainly is an answer.) Since the park’s first full season in 2000, the Mariners have consistently hit for more power on the road, ranking ahead of only the Padres in terms of percentage of overall ISO and SLG they’ve compiled at home:



Mariners percentage of total,

at home, since 2000 Stat Percentage Rank of 30 ISO 95.0% 29th SLG 96.7% 29th Home Runs 46.9% 25th

That span comprises three 90-win teams (including the 116-win 2001 club) and five 90-loss teams (including two that broke 100), so the Mariners have certainly given us a wide sample size of talent to play with. Whether it’s been Ken Griffey & Ichiro Suzuki or Justin Smoak & Dustin Ackley, the park effects are such that the team hits for more power away from Seattle. (By comparison, the Rockies, who unsurprisingly top the majors in all three categories, have 116.0% of their total ISO and 112.4% of their total SLG at home in that time, along with 58.0% of their homers. Coors Field: still really, really good for offense. Safeco and Petco: still not.)

This is known, of course. I haven’t broken new ground here. So with that in mind, here’s the question: What in the world is Kyle Seager doing?

Seager has 12 homers so far this season, tied for fourth among all Major League third basemen; his wRC+ is third, as he takes the step from “solid player” to “star,” even if most fans probably don’t have any idea about it. His improvement is perhaps not unexpected, since his wRC+ has improved from 96 to 108 to 113 to now 133 in his four years in the bigs. This is a young hitter getting better as he gains big league experience. But raise your hand if you saw this happening: Somehow, 11 of the 12 home runs have come in Seattle, in what is always one of the more difficult places for offense, as Robinson Cano would be all too happy to tell you about.

If you’re wondering if any Mariner (with at least 10 homers in a season in the Safeco era) has ever had such a home-heavy homer split, the answer is pretty clear: Nope. And it’s not even particularly close:

The further back you go — the Mariners moved the fences in somewhat prior to last season — the more hilarious some of those percentages get. In 2000, Alex Rodriguez hit 28 homers on the road, but just 13 in Seattle. The year before (and this is presented for entertainment purposes only, as the season was split between the Kingdome and Safeco), Griffey hit 34 homers away from home, and only 14 at home. Seager is doing something no Mariner has ever approached in this ballpark.

But why stop at Mariners? If you were wondering if anyone in any ballpark since divisional play began in 1969 has had a higher percentage, the answer would be yes, but not very many:

Ted Uhlaender! It’s been a good day.

So what’s happening with Seager to have caused this? It’s certainly not the fact that the fences came in, not when you realize that his home run spray chart is this:

While the changes to the fences were this:

Safeco’s 2013 alterations covered roughly three-quarters of the field, ranging from the left-field foul pole to right-center field, many of those a reduction of four feet in distance, as well as lowering the fences themselves by nine feet.

The park changes helped righty batters, but as a lefty pull hitter, Seager is taking aim at the same fences he always has. But despite its reputation, Safeco is doing more to help Seager than it is to hurt him, due to the type of hitter he is. Safeco’s right-field line is two feet shorter than the league average; the wall’s height is three feet lower than average. If you’re a lefty dead-pull guy who can put the ball in the air, Seattle really isn’t a terrible place to be, and that’s what Seager does. When he pulls the ball in the air (at all parks), his HF/FB percentage has been 34.0, 39.6 and 46.2 since 2012.

But then, maybe we’re looking at this the wrong way. Seager hit five Seattle homers in 2012, then eight in 2013, and now he has 11, presumably on pace for more. As he’s improved his hitting and power overall, continued better power at home in a park conducive to it for a player like him is an expected career path. But that fun 91.7 percent number wouldn’t be as interesting if he had more than a single homer (which came at Yankee Stadium) dragging down the percentage, and so maybe the real question here is less about how Seager became the rare hitter to do so well in Seattle, and why he’s become such a disaster on the road. It’s not just about homers: He’s hitting .357/.425/.657 at home and .201/.270/.329 on the road, a reversal of his career splits and a huge difference. Seager, at home, has been the best non-Troy Tulowitzki player in baseball. Seager, on the road, has been the 20th-worst hitter in baseball.

On the road, Seager pounds the ball into the ground more than 40 percent of the time, clearly not playing to his strengths as a lefty flyball hitter, and there’s some obviously unsustainable BABIP numbers in both directions, home and road. For his part, Seager has been completely unhelpful in interviews about it, saying that he’s made no particularly conscious changes in either way, and maybe that’s true. Maybe at some point soon, the home numbers are going to drop down and the road numbers are going to come up to meet them, but even if that happens, and we can no longer make fun lists that point out something absurd like overwhelming power in a purported pitcher’s park, it might not change the overall outcome: In his third full major league season, at 26 years old, Seager has continued an ascent that’s making him into something of a star.

If the Mariners are going to keep up their unlikely playoff run — and right now, we have them second behind the Angels in wild card odds — it’s going to be because a young Seattle hitter finally succeeded where Smoak and Ackley and Jesus Montero and others like them have failed before. If that’s the case, the Mariners may not really care where the homers are being hit.