Three weeks into the 2021 season, the Seattle Mariners have a respectable 13-10 win-loss record. But let’s face it, the Mariners aren’t as good as their record.

I realize my dour assessment won’t sit well with fans, who have rosier outlook about the Mariners’ solid start than me. Maybe time proves me wrong, although I don’t think it will. If the team continues winning, that’s okay with me. But if Seattle actually does regress in the near future, that’s okay too. Please give me a chance to explain this seemingly warped rationale.

First, let’s tackle what’s driving my skepticism about the Mariners’ early-season success. It comes down to one metric – xwOBA. It’s been my go-to stat for several years.

Expected Weighted On-Base Average (xwOBA) is determined by using both the amount of contact and quality of contact (exit velocity and launch angle) made by hitters. A key advantage to xwOBA is defense (good or bad) doesn’t influence it. Therefore, we get a truer sense of how a hitter or pitcher is performing. The current MLB-average xwOBA is .324.

If my explanation doesn’t sway you, consider this. Players with a great xwOBA are among the best in the game. Look at the names topping the xwOBA list for hitters since the beginning of the 2020 season.

Top hitter xwOBA (2020-21)
Bryce Harper .480
Juan Soto .479
Freddie Freeman .454
Ronald Acuña Jr. .447
Mike Trout .441
Fernando Tatís Jr. .423
Corey Seager .422

We can deliberate about the order of the preceding list. But there’s no debate whether these players are among the best hitters in the game. That is a ringing endorsement of xwOBA from my perspective.

When we turn our attention to starting pitchers with the lowest xwOBA, we again find the best and brightest atop the leaderboard. There’s a reasonable chance each league’s Cy Young Award winner is among the following pitchers. After all, both of last year’s awardees are listed below.

Top starting pitcher xwOBA (2020-21)
Trevor Bauer .231
Corbin Burnes .232
Jacob deGrom .236
Gerrit Cole .254
Shane Bieber .257

Hopefully, I’ve done enough to convince the doubters about the value of xwOBA as an evaluation tool. If not, they’ve probably departed this article by now anyway. For those sticking with me, thank you. Let’s use xwOBA to get a sense of how Mariner hitters are performing thus far.


As you might have expected, the usual suspects are leading the lineup – Ty France, Kyle Seager, and Mitch Haniger. They form the top of the batting order and represent 47.8-percent of Seattle’s total hits.

Top Mariner hitter xwOBA (2020)
Ty France .397
Kyle Seager, .383
Sam Haggerty .382
Mitch Haniger .362
Kyle Lewis .351
José Marmolejos .345
MLB xwOBA .324
Dylan Moore .281
Evan White .271
Taylor Trammell .255
Luis Torrens .249
J.P. Crawford .248
Tom Murphy .244

It’s worth noting Sam Haggerty, Kyle Lewis, and José Marmolejos are included on the preceding list despite not being everyday players since Opening Day. We know Lewis, who returned from the IL this week, is going to be a fixture in the lineup. But, barring unforeseen circumstances, Haggerty and Marmolejos will remain as supporting cast members. Still, it takes an entire roster to win ballgames, so I included the duo.

Obviously, having just three hitters (France, Seager, and Haniger) creating so much of the team’s offense is an unsustainable model over the long haul. With one exception, I’m somewhat skeptical about the likelihood of the other players listed above being capable of stabilizing the offense over a full season.

Lewis struggled during the second half of the truncated 2020 season. But as we noted over the winter, it’s reasonable to believe the Mercer product can be a valuable contributor to run production. After that, it gets squishy.

Yes, Haggerty and Marmolejos have been great in small doses. But is it reasonable to expect they’ll sustain their early success over a complete season? Probably not. Perhaps the pair proves me wrong, which is just fine by me. I always root for players to succeed.

Dylan Moore is probably a lot better than his current xwOBA or conventional slash line. But how much better? Entering his season, Moore had 441 career plate appearances spread over two seasons. The reasonable answer is we don’t know what the Central Florida alum’s ceiling is. Not yet, at least.

It’s plausible that no minor-league baseball in 2020 and a late start to this year’s MiLB season have hurt the development of Evan White more than any current major-leaguer. With no safety net to fall back on last year or early this season, White has been forced to self-improve during big-league games. That seems awfully hard to do. Perhaps a brief stay in Tacoma would help the former Kentucky Wildcat hone his skills.

Taylor Trammel has a boatload of promise. But he’s in the same predicament as White was last year. The 23-year-old Georgian must resolve his issues, while being a regular in a big-league lineup. I’m not suggesting Trammell or White need to go to the minors. Much smarter people than me will determine the best path for both players. But at least that option will be available to teams within a matter of weeks.

After White and Trammell, who else stands out as potential rebound candidates? J.P. Crawford has been a marvel in the field. But he’s yet to blend his excellent contact skills with any semblance of extra-base power. As we noted in March, the 2021 season is critical to the 26-year-old’s development and his future with the Mariners.

Both backstops – Tom Murphy and Luis Torrens – may improve offensively. But neither player has a proven record over a sustained period. The right-handed hitting Murphy (533 career plate appearances) has a history of below-average production against right-handed pitchers, although he’s thrived against southpaws.

Prior to the start of the season, we noted Torrens (291 career plate appearances) had an excellent hard-hit rate with the Mariners last September. Perhaps more playing time would help the Venezuelan become more productive at the plate.

Okay, now that I’ve cast a rather large shadow over the lineup, let’s get to the bad stuff.


The injury bug hasn’t been kind to Seattle’s starters. Unfortunately, the Mariners lost James Paxton during the second inning of his first start earlier this month. That’s a difficult loss for the staff and for Paxton the person. Fellow left-hander Nick Margevicius has also landed on the IL with shoulder problems after consecutive starts where he just didn’t look right.

Ironically, Margevicius had the best xwOBA (.325) among Mariner starters prior to his debacle in Boston over the weekend when manager Scott Servais had to pull the southpaw in the first inning. With the Rider product probably out for an extended period, the current top xwOBA spot is currently held by a seemingly unlikely candidate prior to the season – Chris Flexen.

Mariners Rotation xwOBA (2021)
Chris Flexen .332
MLB SP xwOBA .332
Nick Margevicius .353
Justin Dunn .374
Yusei Kikuchi .379
Justus Sheffield .381
Marco Gonzales .410

Flexen appears to be improving with each start, which is an encouraging development for both player and team.

More good news, the xwOBA of Marco Gonzales continues to improve after consecutive solid outings. Another reason to be optimistic about the Gonzaga alum – a combined .301 xwOBA during the 2019-20 seasons.

Justus Sheffield has demonstrated a knack of reaching the sixth inning, which certainly benefits the team. That said, his advanced metrics have been suboptimal this season. Still, a league-average .313 xwOBA during a rookie campaign in 2020 provides a measure of optimism the Tennessean will improve as the season progresses.

With the final two rotations spots, there are more questions than answers.

Justin Dunn doesn’t surrender a lot of hits, but oh those base on balls. The former Boston College Golden Eagle had a high walk rate last season and is surrendering too many free passes in 2021. Moreover, he had a similar xwOBA (.369) to this season’s .374 during 10 starts in 2020. Is it possible Dunn improves with time this season? Absolutely. Is it reasonable to expect a dramatic uptick? Not for me. Again, I hope I’m proven wrong.

Ironically, Yusei Kikuchi had a great xwOBA last year. It was the primary reason I believed the lefty was better than his conventional stats suggested in 2020. Unfortunately, the native of Japan hasn’t pivoted to more success during the first month of the 2021 campaign. In fact, he’s regressed in some ways. With each difficult outing, it seems increasingly unlikely that the Mariners’ decision about Kikuchi’s club option will be a difficult one.


Fortunately and surprisingly, the bullpen has been the strength of the Mariners through their first 23 games. As is the case so many times in baseball, a strong bullpen doesn’t necessarily boast a bunch of household names. This certainly applies to Seattle’s current relief crew.

Mariners Bullpen xwOBA (2021)
Anthony Misiewicz .217
Kendall Graveman .233
Ljay Newsome .261
Keynan Middleton .292
Rafael Montero .297
Will Vest .309
Casey Sadler .310
Drew Steckenrider .321
MLB RP xwOBA .323

Every member of the bullpen who’s faced 20-plus hitters has an xwOBA below the league-average mark for relief pitchers. That’s impressive. Having this kind of quality depth has certainly made Servais’ job a bit easier during this very young season. Even if the bullpen loses Ljay Newsome and his .261 xwOBA to replace Margevicius in the rotation, there’s a lot to like about the relief corps assembled by GM Jerry Dipoto.

Sure, it’s possible the team’s relievers collectively crater at some point. Obviously, health issues can derail any bullpen. But there’s no evidence to suggest the Mariners’ pen will collapse. That’s assuming Dipoto doesn’t trade his best relievers this summer. Sorry, not sorry.


Seattle fans should keep the faith even if my dire warnings of impending collapse become reality. Why? By the end of July, the major-league roster could look considerably different – and better – than it does right now. There’s help on the way.

At some point in the near future, currently injured players like Jake Fraley and Shed Long should be available to return to the Mariners. That’s assuming neither player suffers a rehab setback. Although both Fraley and Long only have a combined 385 career plate appearances, the duo would represent fresh blood for Servais’ lineup and perhaps improved depth.

In the coming months, the Mariners are likely to introduce top prospects Logan Gilbert, Cal Raleigh, and Jarred Kelenic to the majors. Perhaps these youngsters struggle as White and Trammell did. Still, each player represents an upgrade for Seattle over current options on the roster. So even if the kids stumble out of the gate, there’s a reasonable chance the Mariners will be better for having Gilbert, Raleigh, and Kelenic.

So yes, I don’t like what might be waiting around the corner for the Mariners. But I believe there’s a reasonable chance this team will look different and be better by August. Will it be too late for the club to make a late run at a postseason spot?

Maybe. But never say never.

My Oh My…

Got a take on what you just read? Talk about it here!

Image courtesy of Nick Wosika/Icon Sportswire
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Luke Arkins

Luke is a native New Yorker, who grew up as a Mets fan. After the US Navy moved him to the Pacific Northwest in 2009, he decided to make Seattle his home. In 2014, Luke joined the Prospect Insider team. During baseball season, he can often be found observing the local team at T-Mobile Park. You can follow Luke on Twitter @luke_arkins

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