Hoping to re-shape his organization, Seattle Mariners general manager Jerry Dipoto undertook a massive roster overhaul in the offseason. We won’t know for years whether Dipoto’s strategy paid off, but we certainly can discuss how the Mariners are doing through their first 40 games.

What have Seattle’s been successes and disappointments to date?

We’ll try to deliver a coherent answer to this question, plus much more in our three-part Mariners Thru 40 Games Series. We’ve already reviewed the run production effort. Now, let’s talk run prevention.

In The Beginning

As with run production, the effectiveness of the Mariners’ pitching staff has slipped since the team’s tremendous 13-2 start to the season.

M’s Pitching Declines After First 15 Games

First 15 Games
Next 25 Games

Realistically, the staff has taken a step back since mid-April. Nevertheless, it hasn’t been a complete disappointment – unless the expectations of the beholder were set unrealistically high. We’ll get into that shortly. First, a quick sidebar about my metric of choice for our upcoming conversations.

Stat Talk

While the error isn’t an optimal measurement of defensive ability, the Mariners leading MLB in errors by a sizeable margin suggests bad defense could potentially skew pitching numbers. For this reason, expected weighted on-base average (xwOBA) is the right metric to rely on.

Expected weighted on-base average removes defense from the picture by using quality of contact (exit velocity and launch angle) and amount of contact (strikeouts and walks). Therefore, a web gem won’t help a pitcher’s xwOBA nor will a defensive blunder penalize him.

Okay, let’s talk about a starting staff uniquely constructed in an era of flamethrowers.


Only two of Seattle’s starting pitchers – Yusei Kikuchi (93.3 MPH) and Erik Swanson (92.2 MPH) have an average hard-pitch velocity over 90 MPH. As a result, Seattle’s rotation has the lowest average hard-pitch velo of any AL club. It’s not even close.

M’s Rotation Have Softest Tossers in MLB

It’s worth noting the Tampa Bay Rays’ practice of using an opener has something to do with the club leading the AL in velocity race by such a large margin.

Despite having so many soft-tossers, the Mariners’ rotation has been relatively effective at the 40-game mark. Moreover, the staff is delivering better results than it did through 40 contests a year ago.

Rotation Thru 40 Games

.365 (28)
.342 (22)
4.85 (23)
4.48 (19)
4.37 (16)
1.36 (21)
1.27 (15)
.328 (22)
.463 (25)
.461 (23)
7.6 (9)
4.8 (1)
22.4 (13)
17.8 (29)
** MLB Ranking In Parenthesis **

The starting staff is striking out fewer hitters, but has allowed the least amount of walks in MLB. This matters for a cadre of pitchers lacking swing and miss stuff with a tendency for surrendering home runs.

As already noted, Dipoto performed a major makeover on his 40-man roster this past offseason. However, the rotation had the least amount of turnover of any unit. There are new faces, but the holdovers outnumber the newbies – at least for now.

Starter xwOBA Thru 40 Games

Marco Gonzales
Yusei Kikuchi
League AVG
Félix Hernández
Erik Swanson
Mike Leake
Wade LeBlanc

Leading the staff is Opening Day starter Marco Gonzales. Not long ago, we discussed how Gonzales remains effective despite averaging one of the slowest hard-pitch velocities among MLB starting pitchers this year.

While we don’t know for certain how Gonzales’ career progresses in the future, complaining about the Mariners trading former prospect Tyler O’Neill to get the former Gonzaga Bulldog seems passé at this point. Root for Marco, root for Tyler, move on folks.

Gonzales entered the year as the headliner in the rotation, but Kikuchi is quickly acclimating to MLB and beginning to deliver results similar to or better than Gonzales has this year. The Japanese import’s .292 xwOBA ties him with Marco for 20th best in MLB among starters who’ve faced 150+ hitters.

One element differentiating Kikuchi from most big league starters is his team’s plan to occasionally schedule a one-inning start to manage the 27-year-old’s workload. Doing so should help the southpaw transition from pitching once weekly in Japan to every fifth game in MLB.

During Kikuchi’s first abbreviated start, the team recalled top prospect Justus Sheffield to take over afterwards. Things didn’t go well for Sheffield, who surrendered two runs, walked four, and needed 75 pitches to survive three innings of work.

Southpaw Wade LeBlanc is currently on the IL with an oblique strain, but is progressing towards a return to action. LeBlanc tossed a career-high 162 innings for the Mariners last season, but wasn’t particularly effective prior to his injury. Then again, the Alabama alum logged a small sample size before his injury.

Félix Hernández is attempting to transition from his former hard-throwing self to a finesse pitcher. So far, the results are mixed.

Félix has vastly reduced the number of free passes he’s issuing. His 3.2% walk rate is significantly below his career 7.1% BB rate.

On the other hand, the King’s hard contact rate has jumped from 33.9 in 2017 to 43.2 this year. This uptick partially explains a 5.1% home run rate – also the highest of his storied 15-year career.

It’s too early to determine whether the new version of King Félix can deliver consistent results, but his xwOBA ranks in the bottom-third in MLB. Last year, it was in the bottom 6%.

That said; fans should temper expectations. The former Cy Young Award winner is no longer dominant, although that doesn’t mean he can’t help the Mariners or another team.

Another Mariner starter struggling to avoid dingers is veteran right-hander Mike Leake. The veteran right-hander has the highest home run rate (5.3%) among qualified MLB starters. Luckily for Leake and the Mariners, seven of his 11 homers allowed have come with the bases empty. That’s partially attributable to his 4.4% walk rate – seventh best in MLB.

Last year, Leake had a tough beginning with a 6.00 ERA through his first nine starts, but finally improved. Perhaps he rebounds again. After all, the 31-year-old performed very in his last outing against the Yankees.

Then again, Leake’s xwOBA ranks 91 of 94 among MLB starters.

Mike Leake’s xwOBA Trending Wrong Way


Swanson was the less heralded pitching prospect acquired in the trade sending James Paxton to the Yankees last November. Yet, he’s making significant contributions to the big league club before the high-profile arm of the Paxton deal – Sheffield.

Overall, Swanson has performed admirably, but it’s tough to evaluate the 25-year-old after just four starts. He’s completed the sixth inning twice, but the Rangers clobbered him last weekend. In his most recent outing, he surrendered just one hit in six frames against Cleveland.


While the rotation remained stable during Dipoto’s offseason trade blitz, the bullpen did not. Of the eight relievers currently on the 25-man roster at game-40, only two were holdovers from last year – Roenis Elías and Chasen Bradford.

Many faces are new, but the results have been worse for Seattle’s relievers through their first 40 contests.

M’s Bullpen Worse Thru 40 Games

.311 (12)
.345 (28)
4.10 (15)
5.03 (25)
3.94 (13)
4.98 (26)
1.21 (7)
1.48 (26)
.311 (9)
.340 (21)
.406 (19)
.431 (24)
7.6 (2)
12.1 (27)
26.7 (5)
24.6 (14)
** MLB Ranking In Parenthesis **

Hunter Strickland signed with the Mariners in the offseason to be the club’s closer. Unfortunately, Strickland landed on the IL after just three appearances with a lat strain. It’s unclear when the 30-year-old may return to action.

Losing Strickland threw an already volatile bullpen into further disarray. The first reliever to get regular shots at closing was Anthony Swarzak, acquired in the in the deal shipping former closer Edwin Díaz and Robinson Canó to the Mets. Unfortunately, things have not gone well for the right-hander.

It’s a small sample size, but Swarzak has surrendered five home runs and seven walks in 10.1 innings of work this season. His 4.3 HR/9 is the worst in MLB among relievers with 10+ innings this year. Moreover, the 33-year-old’s .417 xwOBA places him in the bottom-10 of 219 relievers.

Definitely a small sample size, but frustrating for Swarzak and Mariners fans.

M’s Reliever xwOBA

Roenis Elías
Mike Wright
Connor Sadzeck
Brandon Brennan
Zac Rosscup
Chasen Bradford
Lge Avg
Cory Gearrin
Anthony Swarzak

After a bumpy start to the season due to control problems, Cory Gearrin has become a stable presence in the relief rotation for manager Scott Servais.

Count on Gearrin getting more opportunities to deliver in the late innings as long as he continues to deliver positive results. That said; it’d be nice if the 32-year-old hurried his pace between pitches, which ranks slowest in the majors.

Elías, a former starter, has quietly become a formidable bullpen weapon for Servais. The southpaw’s .237 xwOBA ranks fourth best among MLB relievers who’ve faced 75+ batters this year.

Zac Rosscup is lethal against left-handed hitters holding them to a .380 OPS in 25 confrontations this year. Conversely, the southpaw hasn’t been as nearly effective versus righty bats (.838 OPS).

The other familiar face from 2018 – Bradford – has proven to be a versatile performer. The 27-year-old righty has made multi-inning outings three times this season, including a 3.1 inning outing. He was sent to Tacoma today, but he’ll be back to help at some point.

Rule 5 pickup Brandon Brennan has been one of the more pleasant surprises for the club. The 27-year-old from the Rockies system has established himself as a valued late-inning/high-leverage asset for his new organization.  

Another low-profile pickup having a positive effect on the relief corps is Connor Sadzeck. Castoff from the Rangers, Sadzeck is missing bats with the 15th highest average hard-pitch velocity (96.7 MPH) among MLB relievers essentially tying him with the Mariners’ former closer – Díaz (96.8)

Mike Wright has made three appearances logging five innings since the Mariners acquired the 29-year-old on April 24. What Wright becomes for his new club is unknown. He’s been decent in the Emerald City thus far, but his .369 xwOBA dating back to the start of the 2018 season suggests a longer look is needed.


Through their first 40 contests, the Mariners have made the most errors (41) in MLB by a large margin – next closest are the White Sox at 33. Seattle also ranks last in defensive runs saved (DRS).

Advanced Metrics Don’t Favor M’s In Early Going

Advanced defensive metrics tend to be more reliable when large sample sizes are available. For this reason, it’s wise to avoid fixating on them after 40 games. Still, the combination of poor advanced and standard defensive stats, plus the eyeball test suggests the Mariners are a well below-average defensive unit.

This doesn’t bode well for pitch-to-contact pitchers to have a sub-par defense behind them. In fact, the Mariners have surrendered 34 unearned runs this year – the Pirates are second with 20. Once again, Seattle holds a big lead MLB in an inauspicious category

Clearly, shortstop Tim Beckham has scuffled in the field at times. However, the injury to Dee Gordon temporarily moves Beckham to second base and hastens the arrival of J.P. Crawford from Class-AAA Tacoma. Assuming Gordon’s injury doesn’t require a DL stint, Crawford’s stay with the Mariners may be brief.

Then again, a prolonged absence by Gordon may lead to Crawford sticking around a lot longer. Assuming he’s honed his glove work in the minors (defense was a concern of Crawford’s former organization), the 24-year-old may never return to Tacoma and eventually supplant Beckham at shortstop.

At third base, Ryon Healy has improved as the season has progressed. Having said that, defense at the hot corner will greatly improve assuming incumbent Kyle Seager returns from the injury list later this month. Where in the field Healy plays after Seager’s return is a mystery for now.

Two areas in the field that may be an issue for the entire season are outfield and catcher – the team ranks last in DRS at both positions. Yes, we’ve already acknowledged advanced metrics are less reliable in small samples. However, the defensive history of two key performers hints the negative trend may continue.

Since 2016, Domingo Santana and his -16 DRS rank 56th among 64 active outfielders with 2,000-plus innings. This year, his -7 DRS in left field is 103rd among 105 MLB outfielders with at least 130 innings played.

The other player with a history of defensive issues is catcher Omar Narváez. Among 21 catchers with at least 150 innings behind the plate, Narváez’s -7 DRS ranks last in MLB.

Narváez also has a history of defensive challenges. Since the 2016 campaign, the Mariners’ Opening Day backstop has amassed -28 DRS placing him 32 of 33 backstops with over 1,500 innings behind the plate.

Both Santana and Narváez are more valuable for their bats than their defense, but improvement is needed. Otherwise, it’s difficult seeing either player being part of the club’s long-term plans.

Looking Forward

Swanson’s presence and Sheffield’s temporary call-up demonstrate the Mariners have more immediate rotation depth in Class-AAA Tacoma than in recent years. And as we suggested previously, the Kikuchi signing may turn out to be a coup for Dipoto.

Having said that, rotation depth could be problematic. After Swanson and Sheffield, the pickings are slim. This could present an issue for the club if they simultaneously lose more than one starter.

As for the bullpen, it’s likely to struggle for the entire season. The relief corps may see some fresh bodies in the coming month assuming Sam Tuivailala and Gerson Bautista don’t suffer setbacks during their injury rehabs.

Still, it’s important to remember any reliever who is performing well is a candidate to be moved by the July 31 trade deadline. That may not sit well with Mariners fans rooting for the 2019 club, but Dipoto has made it clear he’s looking to 2021 to field a contender.

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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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