Mariners fans are all too familiar with the conversation. From the most hardcore to the most casual, all have probably taken part in it or have been prompted to weigh in upon overhearing strangers in animated discussion. “Another former Mariner is crushing it.”

Just last season, The Seattle Times had two columns from Mike Vorel on this topic and took a deep dive into the marine layer’s impact on hitters in Seattle. There’s even a Reddit page dedicated to former Mariners. Anecdotal evidence is all the World Series-starved fan needs, and as Vorel wrote back in April 2024 , “This, truly, is baseball’s unrelenting siren song — the temptation to wonder what could have been, one box score at a time.”

But what if this question could be quantified? What if — using Baseball-Reference Wins Above Replacement (WAR) and a data set encompassing the 21st century — we could find out whether or not Mariners actually perform worse in Seattle than elsewhere?

We did just that.

We compiled a list of 343 players with at least 75 plate appearances or 20 innings pitched from 2000-24, who played for the Mariners and at least one other team. From that list, we assembled each player’s WAR while with the Mariners and while away from Seattle.

WAR is a statistic designed to measure an individual player’s contribution to their team, in terms of wins. Using a player’s hitting, pitching, fielding and base running stats, the WAR number represents how many more wins someone is worth compared to a replacement-level player (e.g. a minor-leaguer who gets called up to fill an MLB roster spot). For example, Ichiro’s 2001 season — for which he won American League MVP and Rookie of the Year — was 7.7 WAR, meaning he accounted for 7.7 more wins than a replacement player. The highest WAR of all-time was 14.1 (Babe Ruth in 1923), and the average WAR for a full-time position player is around 2.0, according to Fangraphs.

There were six different metrics evaluated: Total WAR, pre-Mariners WAR, post-Mariners WAR, awards considerations, first-year WAR with the Mariners and first-year WAR after leaving. (For a full list of qualifiers and notes for this data set, see the bottom of the article.)

The results showed an undeniable truth: Players fared better during their time with the Mariners than with other teams.

Players are significantly worse after leaving Seattle

The narrative around this is predominantly focused on players leaving the Mariners and finding greater success elsewhere. Of all the different factors in the data, the one that overwhelmingly stands out in favor of the Mariners, is just how much players fall off after their time in Seattle.

The average WAR per season of all 343 players with the Mariners was 1.03, and that number drops to 0.71 for those same players upon leaving. While a margin of 0.32 might seem small, it’s significant given the sheer size of seasons (817 with the Mariners, 906 post-Mariners). A whopping 88 players had WARs in the negative after leaving, and only 37 had WARs of 1.0 or better, compared to the 105 players with a WAR of 1.0 or more while with the Mariners. Age and opportunity can certainly be a factor here, as older players may see stats regress or receive less playing time elsewhere. But on the whole, the numbers paint a clear picture that, once they leave, many players never matched their production with the Mariners.

There are the obvious examples driving these numbers in the Mariners’ favor: Ichiro (56.4 WAR in Seattle vs. 3.6 after), Ken Griffey Jr. (70.6 vs. 13.3) and Robinson Cano (23.5 vs. 0.2). There are also plenty of standouts in the opposite direction: Ketel Marte (2.5 vs. 28.7), Adam Jones (0.9 vs. 31.7) and Chris Taylor (0.3 vs. 16.7).

Of the six metrics in the data set, the only one that proved anti-Mariners was that players’ production before coming to Seattle (1.13) was greater than theirs with the Mariners (1.03), and by a much smaller margin. Cano was second on that list with 44.4 WAR in his nine seasons with the Yankees — only to be topped by Rickey Henderson, whose 92 games with the Mariners at age 41 in 2000 qualified him for this list, and his 108.7 pre-Mariners WAR certainly skews the numbers heavily against the Mariners. Even when it comes to awards consideration (All-Star nods, Silver Sluggers, Gold Gloves, or votes for MVP, Cy Young or Rookie of the Year), players had more with the Mariners (10.2%) than the other 29 teams (9.6%).

Year-over-year data won’t save the narrative

OK, so players fared better during their Mariners tenures than elsewhere. But what about recency bias? The guys who came to Seattle and fell off, or left and excelled.

The egregious examples are there for fans to bemoan. Chone Figgins dropped 6.5 WAR in his first year after joining as a marquee free agent from the Angels. Erik Bedard dropped 4.6 in his debut season after a high-profile trade that sent the aforementioned Jones to Baltimore. Most recently, Teoscar Hernandez saw his WAR jump from 2.1 with the Mariners in 2023 to 4.3 last season with the World Series-winning Dodgers. Hall of Fame third baseman Adrian Beltre even drives the data negatively on both ends, with both the second-highest drop upon joining the Mariners (9.6 with the Dodgers in 2004, 3.2 with Seattle in 2005) and departing (3.3 in 2009 with the Mariners, 7.8 with Boston in 2010).

Take out the anomalies, though, and once again the Mariners come out on top. In players’ first seasons with the Mariners, they gained a total of 11.4 WAR. In their first season after departing, they lost 24.3. There were 197 cases of players either gaining WAR in their first season with the Mariners or losing WAR in their first year after leaving, compared with 163 going in the opposite direction.

Mariners hitters actually outperform pitchers

Hitters generally have higher WARs than pitchers, and the home/road splits for Mariners hitters are a reflection of the difficulties of hitting in Seattle at T-Mobile Park (Mariners team OPS at home was only higher than on the road four times in the past 20 years). For the purposes of this exercise, however, it’s the batters who are carrying the weight for the Mariners-positive results.

When isolating just hitters, players had a WAR of 1.32 with the Mariners and 1.16 all other teams. Compare that to pitchers, who are at just 0.63 WAR in Seattle but 0.73 elsewhere. The biggest split when separating these two is in the year-over-year stats. Hitters who have left Seattle suffered a 31.5 WAR drop in their first season on a new team, whereas pitchers increased by 9.1. The adjustment to joining the Mariners for the first year is the most affirming of the perception of playing here, with hitters losing 13.1 WAR in their debut seasons and pitchers gaining 21.3.

On the awards front, hitters received recognition or major awards votes in 14.5% of seasons (12.9% with other teams), while pitchers were at just 4.5% (5.5% elsewhere). Though he doesn’t stand out as an anomaly in either direction like others mentioned before, Nelson Cruz deserves some recognition as the only player to carry a 100% awards track record in more than one season in Seattle (Michael Pineda and Cliff Lee each did it in their only season). In his four years with the Mariners, Cruz was a three-time All-Star, two-time Silver Slugger winner and received MVP votes in three different seasons. His WAR per season of 4.28 with the Mariners ranked fifth among all players, behind only Alex Rodriguez (5.44), Griffey (5.43), Cano (4.7) and Mike Cameron (4.6).

Final thoughts

As to why these results are what they are, the answer is more unknowable. Certainly, the fact that the Mariners made the playoffs only three times in this quarter-century-long sample size is driving the opposite narrative.

A generous read would be that the Mariners are far better at drafting and developing talent than they’re given credit for, because we know, at least during Jerry Dipoto’s tenure running the front office, the Mariners have lost 26.4 WAR via trade. A more pessimistic view would be that these players just aren’t as good as other teams’ rosters during this time frame, and that they were given more at-bats and innings in Seattle than other teams were willing to give. Players like Yuniesky Betancourt (3.4 WAR with the Mariners vs. -5.8 elsewhere), Willie Bloomquist (3 vs. -1.4) and Tom Wilhelmsen (5.8 vs. -1) stand out in that regard.

The subjective arguments will always be there, but the objective data remains: The numbers are indisputable that, in the 21st century, players have performed better with the Mariners than they have for MLB’s other 29 teams.