Contenders always strive to bolster their starting rotation prior to the MLB trade deadline. The most treasured arm is the starter capable of leading a team deep into the postseason. That said, the upstart Seattle Mariners aren’t quite ready to pursue such a pitcher.

Still, at some point, the Mariners will need to upgrade the rotation to become a full-fledged postseason contender. Waiting until the offseason is a reasonable approach. Then again, why not start now? That’s assuming an opportunity presents itself.

Just for fun, I identified 16 rotation trade targets that could make sense for the Mariners. At least I think they could.

Since we don’t know whether ownership is amenable to adding payroll, my list includes both prominent names and fringe candidates. Each is enjoying varying levels of success and remains under club control for different lengths of time. Therefore, the cost of acquisition depends on the individual’s circumstances.

Please note we won’t be discussing pending free agents. Instead, the focus will be on pitchers capable of helping the Mariners now and in future seasons. Similar to the strategy GM Jerry Dipoto employed when adding Marco Gonzales and Mike Leake in the summer of 2017.

Having said that, it’s very possible Dipoto sees things differently than me when it comes to acquiring rentals. After all, he and his staff are much more intelligent and savvier than this dumb blogger. But considering the team’s commitment to the future, Seattle isn’t likely to overpay for a player destined to walk after the season. That much seems certain.

With each player’s profile, you’ll see the same set of stats with MLB averages. Please note the column labeled “Thru” refers to the last season under club control prior to free agency, including option years.

Let’s start with the most obvious choice for many fans.


German Márquez, RHP – Rockies

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2024
26
3.59
24.4
9.0
.278
.298
MLB
4.20
23.2
8.0
.314
.323

Márquez has been Colorado’s ace and could potentially fill the same role for contenders or clubs looking to the near-future. The Venezuelan is an innings eater, who leads the majors with three complete games. Not only that, he almost threw a no-hitter at Coors Field last month.

Fun fact: 10 teams don’t have a pitcher with a complete game this year, including the Mariners

Making Márquez even more appealing, a team-friendly contract. This year, he’s earning $7.8 million with a raise to $11.3 million next season and then $15.3 million in 2023. After that, there’s a $16 million club option for the 2024 campaign.


Sonny Gray, RHP – Reds

Thru
Age
ERA
K%
BB%
AVG
xwOBA
2023
31
3.19
30.3
8.3
.304
.292
MLB
4.20
23.2
8.0
.314
.323

With the Reds still in the NL Central and Wild Card races, it’s quite possible the team won’t move players this month. Still, Gray is earning $10.2 million annually in 2021-22 with a 2023 club option costing $12 million. Perhaps Cincinnati entertains moving the Vanderbilt product, if reducing payroll became a priority.

Gray would be an excellent fit for the Mariners. Other than two rocky years with the Yankees, he’s been excellent with Oakland and now Cincinnati. The right-hander would also serve as a veteran presence with something left in the tank – qualities Dipoto has coveted for his staff.

Note: Gray is on the IL with a rib cage strain, although he’s not expected to be out for an extended period. As long as this holds true, the injury shouldn’t deter a forward-looking team from acquiring the 2011 first round pick of the A’s.


Tyler Mahle, RHP- Reds

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
26
3.68
29.5
8.8
.301
.290
MLB
4.20
23.2
8.0
.314
.323

Again, the Reds may be wary of dealing a starter with a potential berth still conceivably within reach. Especially Mahle, who is seemingly entering his peak and earning a relatively affordable $2.2 million salary. If Cincinnati were to trade the Californian, the buyer acquiring him could be asked to offload more prospect capital than expected in a Gray deal.


Aaron Nola, RHP – Phillies

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
29
4.53
29.6
5.2
.314
.303
MLB
4.20
23.2
8.0
.314
.323

Will the Phillies sell at the deadline? They’re hovering near the .500-mark with several teams in front of them in the NL East and Wild Card races. Assuming Philadelphia went into sell-mode, it has two pitchers that I find interesting. The first is Nola.

Nola’s ERA is over 4.00 for the first time since 2016, although advanced metrics assure us that he’s still an above-average starter. The former LSU Tiger remains adept at missing bats and has completed six-plus innings in half of his 18 starts, including a complete game in April.

The 2018 All-Star and Cy Young Award finalist is due $15.5 million next season with a $16 million club option for 2023.


Jordan Montgomery, LHP – Yankees

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
28
4.16
24.5
7.2
.297
.316
MLB
4.20
23.2
8.0
.314
.323

Yes, including a New York Yankee is definitely an outside-the-box move. Even if New York chose to sell, dealing a starting pitcher under club control through 2023 may not be on the team’s agenda. That said, Montgomery is an interesting player.

After missing most of 2018-2019 due to Tommy John surgery, Montgomery’s 2021 numbers suggest the former South Carolina Gamecock is finally fully recovered. Still, there is some risk with acquiring a 28-year-old pitcher, who’s made 20-plus starts just once. On the bright side, his $2.1 million salary should fit into any budget.


José Berríos, RHP – Twins

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2022
27
3.36
25.7
6.5
.290
.316
MLB
4.20
23.2
8.0
.314
.323

Berríos is having a solid campaign despite playing for a team that’s cratered. Perhaps Minnesota begins to re-energize its farm system by dealing the two-time All-Star this summer. A word of caution. His 3.36 ERA looks much better than an .316 xwOBA that suggests he’s been a little better than league-average.

Still, Berríos has been a durable performer during his six-year MLB career. This season, he’s pitched through the sixth inning in 10 of his 18 starts. Furthermore, the native of Puerto Rico is relatively inexpensive – $6 million in 2021 with one year of arbitration eligibility remaining.


Luis Castillo, RHP – Reds

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
28
4.81
21.3
8.7
.320
.315
MLB
4.20
23.2
8.0
.314
.323

Oh look, another Red. As with Mahle, Castillo is in the first year of arbitration eligibility and receiving a relatively low salary – $4.2 million. Based on xwOBA, the native of the Dominican Republic has been slightly above average this season. That said, consider how much better the Mariners’ rotation would look right now with Castillo in it.


Zach Eflin, RHP – Phillies

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2022
27
3.88
22.4
3.3
.321
.296
MLB
4.20
23.2
8.0
.314
.323

The 25-point difference between Elfin’s wOBA and xwOBA suggests he may be the victim of Philadelphia’s defense, which ranks 29th in defensive runs saved. Other appealing aspects of his game include a league-leading 3.3-percent walk rate and the fact he’s averaging six innings/start. The Floridian is grossing $4.5 million this season with one more year of arbitration eligibility remaining.


Kyle Hendricks, RHP – Cubs

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
31
3.77
18.0
4.3
.331
.340
MLB
4.20
23.2
8.0
.314
.323

In a way, Hendricks is a right-handed version of Gonzales. Neither throws hard or strikeouts a lot of batters. Both are most effective when they limit walks. Hendricks has certainly done this lately. The Dartmouth alum’s 3.3-percent walk rate spanning the last two seasons is the lowest among qualified starters. Still, it’s important to recognize he’s leading the NL home runs allowed and has an unappealing .340 xwOBA.

It’s plausible the combination of financial obligations and Hendricks’ 2021 lackluster numbers deter teams from pursuing him. The California native is earning $14 million now through 2023. There’s also a $16 million club option for 2024, his age-34 season.


Kyle Gibson, RHP – Rangers

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2022
33
2.29
21.7
7.6
.262
.290
MLB
3.20
23.2
8.0
.314
.323

The Missouri alum’s name figures to be prominent in trade speculation this month thanks to his outstanding numbers and the fact he’s making $10 million this year and only $7 million in 2022. Still, the issue for me is whether Gibson’s recent success is sustainable moving forward.

Gibson’s ERA, wOBA, and xwOBA are all career bests by a large margin. Is it reasonable to expect a 33-year-old to deliver similar production next season when he’s a year older? That’s a critical question teams must confront. Prior to this year, the Indiana native had a 4.57 ERA through his first eight big-league seasons. Furthermore, his .327 xwOBA since 2015 isn’t even close to the .313 MLB-average during this period.

The financial risk of acquiring Gibson is relatively low. However, a team acquiring him could overpay in prospects only to be disappointed with his 2022 production.


Kenta Maeda, RHP – Twins

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
33
4.66
24.0
7.8
.338
.315
MLB
4.20
23.2
8.0
.314
.323

After finishing second in Cy Young Award voting last season, Maeda’s numbers have significantly regressed. So much so, the native of Japan is on a path to set career worsts in every category listed above. Still, his .315 xwOBA suggest there’s a glimmer of hope he could be better-than-average in the second half of 2021.

If the Mariners acquired Maeda, it’s possible he’d be just one more pitcher unable to finish five innings on a regular basis for manager Scott Servais. Then again, a change of scenery might help get the 33-year-old back on track. Even if Maeda didn’t work out for Seattle, his $3.1 million annual salary over the next two seasons isn’t exactly a budget-breaker.


JT Brubaker, RHP – Pirates

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2025
27
4.47
23.7
5.1
.323
.324
MLB
4.20
23.2
8.0
.314
.323

Brubaker is inexpensive and under club control for the next four seasons. A low-revenue club like the Pirates may not want to keep the University of Akron alum on its roster for budget reasons. That said, the sophomore could be a stabilizing presence in Seattle’s 2021 rotation and potentially capable of providing value moving forward.


Antonio Senzatela, RHP – Rockies

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
26
4.58
15.7
5.1
.342
.327
MLB
4.20
23.2
8.0
.314
.323

Getting Senzatela away from the un-friendly confines of Coors Field might benefit him and ultimately his new club. Although the Venezuelan doesn’t miss bats at a high rate, he’s miserly with surrendering free passes. His 5.1-percent walk rate is ninth lowest among qualified starters. As with most of the arbitration-eligible players we’ve discussed, Senzatela’s salary is a very affordable $3 million.


Merrill Kelly, RHP – Diamondbacks

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2024
32
4.60
20.7
5.3
.316
.325
MLB
4.20
23.2
8.0
.314
.323

Initially an eighth round pick of the Rays in 2010, Kelly eventually signed with SK Wyverns of the KBO prior to the 2015 season. He eventually made his MLB debut with Arizona in 2018. Considering his advanced age, the Arizona State product may not be a long-term fixture in a future contender’s rotation.

Then again, Kelly has completed six innings in 11 of 18 starts this season. And let’s not forget that the Mariners have enjoyed success by signing a player returning from Korea – Chris Flexen. Financially, the Texan is making $4.25 million this season with a $5.25 million club option for next year. After that, there’s the possibility of two years of arbitration-eligibility.


Alec Mills, RHP – Cubs

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2025
29
4.84
19.0
7.6
.334
.325
MLB
4.20
23.2
8.0
.314
.323

Although Mills began the season as a reliever, he shifted to the rotation in mid-June and has a 3.65 ERA in five starts. Since joining the starting staff, he’s striking out hitters at a higher rate (24.3-percent) and giving up less walks (5.8-percent). Perhaps the Tennessean is the kind of arm Dipoto needs to pursues to help the 2021 Mariners.

First, Mills has proven capable of shifting between the bullpen and rotation. Furthermore, beginning the season as a reliever may mean the right-hander has more miles remaining on his arm than starters in the rotation since Opening Day. Then again, the North Siders could keep Mills for his versatility and the fact his first year of arbitration eligibility isn’t until 2022.


Caleb Smith, LHP – Diamondbacks

Thru
Age
ERA
K%
BB%
wOBA
xwOBA
2023
29
4.02
25.4
11.6
.309
.345
MLB
4.20
23.2
8.0
.314
.323

Smith has also started and relieved this season, although his numbers aren’t as impressive. The Sam Houston State product has been far more effective as a reliever with a 2.70 ERA and impressive .307 xwOBA. Someone as adaptable as Smith could help the Mariners shore up the backend of the rotation or help stabilize the bullpen. The Texas native is making $1.5 million this season with two arbitration years remaining.


Based on my terrible record of identifying potential Dipoto trade targets, there’s a pretty good chance that none of the names I’ve mentioned will be wearing a Mariners uniform by August. Still, my view that Seattle can’t reach the 2021 postseason without getting better results from the starting staff remains unchanged.

Adding controllable rotation upgrades could potentially help the Mariners overcome the slim odds of the team playing meaningful October baseball this year. At the very least, augmenting the major-league roster would send a clear signal to players and fans that the organization is committed to continuous improvement in 2021 and beyond.

At this point, fans deserve that much from ownership.

My Oh My…

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

Image courtesy of Ted S. Warren, licensed via AP Images
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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

4 Comments

  1. The Mariners payroll is actually projected at $92.3M, not $73M. The revolving 40-man counts, and there are always more than 26 players being paid big-league money because players get paid in full while on the IL.

  2. Author

    Hey Pat. Thanks for reading. The Mets are in first place. They’re not trading anyone capable of helping them get to the postseason. Adding relief help wouldn’t hurt. But the bullpen can’t cover enough innings, if 40% of the rotation is unreliable or unproductive.

  3. Our payroll is around $73M for the 2021 season, halfway through the year means money eill be less of a factor.
    Trade ideas…
    Cruz (DH), Donaldson (1B/3B), Rogers (LH SU) & $12M for Dunn, Carlson & Gerber.
    Bryant (LF/3B/1B), Kimbrel (CP), Steele (LHP) + $4M for Trammell, Sheffield & Stoudt
    K. Marte (2B/OF) for France, Kirby, Bauers, Then & Margevicius
    Gallo (OF), Gibson (SP) & Kennedy to Padres; Gore (LH SP), Morejon(LH SP), Marcano (2B/SS) & Campbell (SP) to Rangers; Snell (LH SP), Diaz (RH SP), Leclerc (RH SU) to Mariners.
    Depending on how everyone plays down the stretch or how injuries occur, we’ll have more than enough overlap to cover injuries or pther issues. All trades were run through http://www.baseballtradevalues.com, a great site for hypothetical trades who truly nails real baseball player excess values and has many examples they show as proof for their formula.

  4. What about bringing in a closer or a set up guy? I’d love to get Diaz and Trevor May taking the set up role.

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