Marco Gonzales Mariners

The 2021 Seattle Mariners are a fun group to watch. Even better, a strong June has the Mariners boasting a 45-40 record on the Fourth of July. Naturally, the team’s recent success has created a groundswell of interest in the upstarts from the Pacific Northwest. But is their success sustainable?

It’s a bit early to have illusions of grandeur about the Mariners’ season. But if the team is going to have any chance of legitimately vying for a playoff berth in 2021, the starting rotation must be better than its current version, which ranks in the bottom-third of the majors in multiple categories.

M's Rotation Stats & MLB Rankings
QS
ERA
HR%
K%
BB%
AVG
wOBA
xwOBA
SEA
26
4.60
3.1
20.6
8.5
.252
.327
.350
Rnk
20
23
20
21
24
21
20
27

Injuries have undoubtedly affected the rotation in a big way. James Paxton, Nick Margevicius, and Ljay Newsome have all experienced season-ending injuries. Making matters worse, Opening Day starter Marco Gonzales, who’s previously undergone Tommy John surgery, was lost for a month after suffering a forearm strain. Gonzales has since returned, although Justin Dunn is currently sidelined with a shoulder strain. That’s a lot of starting pitching to lose in one season.

Still, for a postseason contender, it’s immaterial who’s not available. What matters are the players the team will rely on during the dog days of summer. For Seattle, that appears to be Gonzales, Dunn, Yusei Kikuchi, Chris Flexen, Justus Sheffield, and rookie Logan Gilbert. As a whole, this unit hasn’t fared particularly well this season. That’s a problem.

A closer look reveals that the Mariners’ rotation can be split into two halves – productive and reliable contributors and the other guys. Through the midway point of the season, manager Scott Servais has routinely received positive outcomes from Kikuchi, Flexen, and Gilbert. Meanwhile, Gonzales, Dunn, and Sheffield have dealt with ineffectiveness and/or injury.

M's Jekyll & Hyde Rotation
GS
QS
ERA
HR%
K%
BB%
AVG
wOBA
xwOBA
Kikuchi/Flexen/Gilbert
38
19
3.61
3.2
22.0
6.4
.234
.293
.315
Gonzales/Sheffield/Dunn
35
6
5.25
4.1
19.7
10.1
.268
.356
.387

In his third year in MLB, Kikuchi has emerged as Seattle’s best pitcher and an All-Star. Not only that, he’s making a strong case for the Mariners to exercise a club option that would keep the 30-year-old in the Emerald City through the 2025 campaign. At the moment, the organization doing so seems like a no-brainer.

Unheralded before the season and even now, Flexen is proving to be an amazing find by GM Jerry Dipoto and his staff. After pitching in Korea in 2020, the 27-year-old has unexpectedly helped anchor the Mariners’ rotation along with Kikuchi.

Since debuting on May 13, Gilbert has lived up to the billing as Seattle’s top pitching prospect. Sure, he struggled out of the gate. But the 24-year-old has since gained his footing and managed to hold opponents to a .209 AVG and log a 2.90 ERA in six starts since Memorial Day.

Dunn struggled with his control since joining the Mariners organization in December 2018. But he appeared to be turning a corner in his development before a balky shoulder affected his performance and eventually his availability. The right-hander is beginning to throw again and expected to return to the club sometime after the All-Star break.

Gonzales and Sheffield rank in the bottom 10-percent among starters in ERA, FIP, wOBA, and xwOBA and appear to be getting worse as the season progresses. Unless the pair begins delivering positive contributions on a more regular basis, it’s to tough envision the Mariners competing for a postseason spot in 2021 with its current roster.

Consider this. Since Gilbert’s May 13 debut, the Mariners have a 27-21 record. That’s fifth best in the AL behind Houston, Boston, Tampa Bay, and Chicago. Great news, but the rotation’s combined numbers continue to remain in the lower-third of the league despite the team’s winning ways. Again, the Jekyll and Hyde analogy applies.

M's Rotation Since May 13
GS
ERA
HR%
K%
BB%
AVG
wOBA
xwOBA
Kikuchi/Flexen/Gilbert
27
3.34
3.2
22.4
6.5
.222
.284
.310
Gonzales/Sheffield/Dunn
18
5.93
4.8
20.3
9.9
294
382
.402

Kikuchi, Flexen, and Gilbert have essentially carried the rotation for the last six weeks. Meanwhile, the other three main starters have struggled and made significantly fewer starts than their counterparts. For further proof of each group’s value to the team’s record, let’s consider how the Mariners have done when they’ve started games.

Although we know pitcher wins aren’t an effective measure of starting pitchers, how a team fares with a specific starter on the mound may tell us something about his value to the team. With this in mind, take a look at the win-loss record of the Mariners when our two groups and several substitutes started games since Gilbert’s debut.

Seattle’s Record Since May 13
Kikuchi/Flexen/Gilbert (18-8)
Gonzales/Sheffield/Dunn (8-10)
Others (1-3)

The Mariners appear to have a much better chance of winning games started by Kikuchi, Flexen, or Gilbert. It’s also worth noting the team is 7-1 in Gilbert’s last eight starts.

Realistically, there are two outcomes for the rotation that lead to a potential postseason run this season. At least two of the three struggling arms – Gonzales, Sheffield, and Dunn – dramatically improve after the All-Star break. Or, Dipoto gets help from outside the organization to bolster the starting staff. Otherwise, it’s unlikely the Mariners play meaningful October baseball in 2021.

Yes, it’d be cool if Dipoto added a few hitter to bolster the lineup this summer. Who wouldn’t want to see a reunion with fan-favorite Nelson Cruz? Adding “Boomstick”, or any other potent bat, would certainly benefit the Mariners. But doing so won’t matter if the rotation continues to underperform.

Perhaps Dipoto acquires rotation help this summer in the form of rentals or players with club control remaining. But doing so won’t be easy. As we’ve discussed before, pitching is the number-one commodity every contender is looking for during deadline deal season. If the sixth-year GM doesn’t add any arms, his team’s 2021 postseason outlook will rest on the arms of his current starting pitchers.

Understandably, fans are eager to see the organization’s 20-year postseason drought come to a end. But the Mariners are just now emerging from their rebuild phase. Dipoto isn’t likely to squander significant prospect equity for a fleeting shot at a wild card berth, which is essentially a play-in game. After all, 2021 was always going to be a season of discovery for Seattle.

So what have we discovered about the Mariners thus far? They’re an exciting young ball club worthy of our attention this summer. We’re also learning the team needs more starting pitching to take the next step in its transformation – become a sustainable postseason contender.

My Oh My…

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

Image courtesy of Cody Glenn/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

1 Comment

  1. That’s a pretty good convincing analogy. If, and when Dunn gets back, and Gonzales rights himself that will surely help. They need to find another contributor for sure, another surprise still may come within or a trade could be a possibility. It’s not as though they don’t have the ammunition.

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