AL West Primer: Mariners pitching
The team with the best pitching staff likely wins the AL West. Could the Mariners be that team?
The final segment of our AL West primer series tackles the Seattle Mariners pitching staff. Let’s begin with a refresher on the staff’s performance last year.
Armed and ready
As we noted in the Mariners lineup primer, the offense sputtered throughout the season. Conversely, Seattle’s pitchers propelled the team to the postseason for the first time since 2001. Other than surrendering a lot of home runs, the staff was top-10 in multiple categories.
The rotation’s .314 xwOBA suggests it was mid-pack compared to other staffs. Still, three Mariner starters did have an above-average xwOBA: George Kirby (.284), Luis Castillo (.290), and Robbie Ray (.295). Furthermore, Logan Gilbert (.314) was close to league-average.
Expected Weighted On-Base Average (xwOBA) uses quality of contact (exit velocity and launch angle) to determine what should’ve happened to batted balls. A key advantage to xwOBA is defense (good or bad) doesn’t influence it. This gives us a truer sense of how a hitter or pitcher is performing. Last year, the MLB average xwOBA = .309
Meanwhile, the bullpen was among the best in baseball (.279 xwOBA). Only the Los Angeles Dodgers (.272) rated better than Seattle. All told, the Mariners had seven relievers who faced 100-plus hitters and record a better-than-average xwOBA.
Last year’s breakout star in the bullpen was Andrés Muñoz, who established himself as one of the best relief arms in baseball. Former Mariner Edwin Díaz (.202) was the only reliever with a better xwOBA than Muñoz. The most encouraging fact about the right-hander: he’s only 24-year-old.
Of the names listed above, only Erik Swanson won’t be a Mariner this year. He was dealt to Toronto in exchange for right fielder Teoscar Hernández. The other notable pitcher no longer with the club is Matthew Boyd.
Thanks to the efforts of President of Baseball Operations Jerry Dipoto and GM Justin Hollander, the organization’s starting pitching is talented and deep. Barring injury or unforeseen circumstances, the top four rotation spots are etched in concrete.
Although their experience levels greatly differ, the veteran Castillo and sophomore Kirby enjoyed great ends to the 2022 campaign. The expectation for the foreseeable future is the duo anchoring the top of rotation. At least, that’s my expectation.
To demonstrate this point, I compared Ray’s stats when facing Houston to his numbers against the seven other postseason teams he faced, plus wild card challenger Baltimore. Those clubs were Atlanta, Cleveland, both New York teams, Philadelphia, Tampa Bay, and Toronto.
Ray vs Astros - 3 starts / 10.2 IP / 10.97 ERA / .442 AVG / .440 xwOBA
Ray vs others - 10 starts / 60.2 IP / 3.26 ERA / .201 AVG / .293 xwOBA
Obviously, getting clubbed in three games by the opponent your team is trying to overtake in the division is suboptimal. But this doesn’t change the reality Ray was a valuable starter last year. To suggest otherwise is silly talk.
There’s a lot to like about Gilbert and what he can mean to the rotation. But opponents had a 45.6% hard-hit rate against him. Only Colorado’s Germán Márquez allowed more hard-hit balls (265) than the Stetson alum (245) did last year.
Granted, many of Gilbert’s stats look good or better: 3.20 ERA, 3.46 FIP, .242 AVG, .299 wOBA. But the amount of loud contact the right-hander has allowed as a big-leaguer (45.2% hard-hit rate in two seasons) is troublesome for me. Allowing fewer hard-hit balls might elevate Gilbert to top-of-the-rotation status rather than third or fourth best starter in a good rotation.
As it stands, Marco Gonzales seems to hold the edge over Chris Flexen for the number-five spot in the rotation. Naturally, this could change between now and Opening Day due to health, performance reasons, or a trade. But assuming Gonzales earns the final spot, Flexen likely heads to the bullpen as he did when the team acquired Castillo last August.
Beyond the six starters we’ve already discussed, there are talented arms waiting in the wings to help if the need arises.
One fact this nerd likes about Miller: he made 26 starts and logged 133.2 innings last year. This suggests to me the 24-year-old is MLB-ready from a workload perspective. Taylor Dollard also checks the same box with 27 starts and 144 innings with Class-AA Arkansas.
Last year, Hancock threw a career-high 98.1 innings. That said, the organization has the brain power to manage his workload when the right-hander eventually raises his game. Much like it did with Kirby in 2022.
Prelander Berroa is an interesting arm acquired last May from San Francisco for reserve infielder Donovan Walton. It’s too early to tell whether the 22-year-old remains a starter or becomes a high-leverage reliever. But he’s someone to watch this season.
After spending 2021 in the minors, Gott pitched for the Brewers last year. Naturally, I’m impressed by his .284 xwOBA, which was second-best in Milwaukee’s bullpen. The 30-year-old also held opposing hitters to an impressive 31.5% hard-hit rate.
Injuries have slowed Topa’s career, who’s thrown just 18.1 MLB innings. But he’s produced a high ground ball rate in the minors and boasts a good history of limiting walks. The 32-year-old also has minor-league options remaining, which provides the team with added roster flexibility.
Casey Sadler - NRI
J.B. Bukauskas - NRI
Nick Margevicius - NRI
Taylor Williams - NRI
Riley O'Brien - NRI
Of the top relievers listed above, Brash is the most enigmatic to me. As Pitching Ninja highlighted during last October’s ALDS, the right-hander’s slider is extremely nasty. Still, I have a concern.
Brash has struggled with his command and control during his young career. For this reason, I’m not as high on the 24-year-old as others are. Not yet, at least.
Year Level BB%
2021 AA-A+ 11.9
2022 AAA 13.1
2022 MLB 14.9
Don’t get me wrong. Brash can be an important contributor to the 2023 bullpen. In many ways , the Mariners need him. But to reach the heights he achieved late last season, the Canadian must keep his walk rate in check. I’m rooting for Brash to do so.
See you in October?
The Mariners offense should be much better than the 2022 version or the year before. Plus, the rotation could be tops in the AL West and perhaps one of the best in baseball. Similarly, the bullpen has a chance to be elite once again. All of this makes for a great foundation of a World Series contender.
Naturally, injuries can derail a roster. So can unexpected poor performances from key contributors. But every organization faces the same challenges and the Mariners are generally well-equipped to deal with unforeseen major setbacks.
Can the Mariners overtake the Astros to win the AL West?
As of today, the safe and proper answer is no. But Houston’s primer did identify potential stumbling blocks, which could prevent the club from running away with the division again.
Realistically, the team with the best starting rotation will win the AL West. For this reason, the Mariners definitely have a chance to win a division title for the first since 2001.
My Oh My…
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