Previewing the Mariners six-man rotation

The 2020 Seattle Mariners are going to go with a six-man rotation during the COVID shortened season. This decision gives them greater flexibility to get some of their younger pitchers experience, while also managing their innings and allowing the team to work a pair of veterans in.

The news about the rotation broke a few days ago during a zoom call between general manager Jerry Dipoto and the media.

With the lack of an organized Spring Training schedule, there just isn’t enough time for the pitchers to get their arms stretched out for a season’s worth of starts…even just a 60-game one. It makes sense to go with the six-man staff in order to increase the number of rest days between starts.

It will be interesting to see how manager Scott Servais uses this rotation, and how his managerial decisions will be impacted by the innings limits on some of its younger (and newer to MLB) starters.


The projected rotation

Marco Gonzalez: The veteran starting pitcher is entering his third season with the Mariners, and is coming off the best season of his career. In 2019, Gonzalez was worth 3.7 wins with an ERA of 3.99, a FIP of 4.15, and a career low home run to fly ball ratio of 9.3%. He pitched more to contact last season — a career high of 77.3% as a starter — while holding his opponents to a batting average of .261 (his best in a full season).

The best thing to come out of last season for Gonzalez was his durability. His 34 starts last season were tied for first, and the 203 innings pitched were the highest of his career. While he won’t come any where near those numbers in 2020, look for him to show continual improvement as he enters his prime.

Kendall Graveman: The 29-year old missed the entire 2019 season due to Tommy John surgery, the year after his 2018-season was cut short due to reconstructive elbow surgery. Seattle originally signed Graveman to a one-year minor league contract. Prior to the COVID19 shut down, the reports out of spring camp were encouraging.

With the scrubbing of the full Spring Training and the MiLB seasons, it’s likely that Graveman will start the abbreviated 2020 season in the starting rotation. He’s the member of the staff most likely to benefit from the shortened season as well as the six man rotation. This will be good chance for him to work his arm back into major league shape, without a high inning workload or going on only five-days rest.

Yusei Kikuchi: After an up-and-down rookie year, Kikuchi is going to have work on being more consistent with his mechanics. He spent most of last season tinkering with them, which led to inconsistency with his commend as well as his velocity. Even with this shortened season, it’s going to be vital that we (and the front office) see Kikuchi’s consistency from start to start improve. Otherwise, the rotation could be in serious trouble going forward.

Taijuan Walker: The former Mariner is back on a minor league contract following an injury shortened 2019 & 2018. Walker is only 27-years old and his slider looks like it could still be an effective pitch. He has only pitched in four games since his last full season back in 2017, including a promising start in Cactus League play back in March.

Like Graveman, Walker is going to benefit from the shortened season and the team’s six-man rotation. With more rest in between starts this will be a great chance for him to work on testing the durability of his shoulder, while potentially making a case for being part of the franchise’s future plans.

Justin Dunn: Justin Dunn made his major league debut last season, and what we saw was tantalizing; but brief (6.2 innings across four starts). Servais primarily used him in the opener role during his time with the big league club, which was a good way to introduce him to the show.

While his low inning count doesn’t give us enough data to truly judge how he did last season (via ERA, FIP, and xFIP), his high walk rate is something to be concerned about as we enter the 2020 season. There needs to be significant improvement there if he’s going to be a reliable option for Seattle in the future.

Justus Sheffield: The rookie got his first real cup of tea at the major league level, as he started in seven games last season. In those 36 innings, his performance was erratic and hampered by poor luck with batted balls — opposing bats had a BABIP of .371 against him last season, yikes. While the sample size is too small for him as well, his high strike out rate (22%) and relatively low walk rate (10.7%) is promising.

Expect to see him with more innings this season, but still be under an inning limit as the franchise continues to work towards a contention window of 2021 or 2022. If he can get have some better luck with batted balls, while also capitalizing on that high strikeout rate…the ceiling is high for the 24-year old.


Season outlook

The good news is that there is significantly more upside to this starting rotation than there was to the rotation Seattle started with in 2019; the bad news is that five out of the six pitchers are likely to be on inning limits that will prevent them from going too deep into ball games, despite the shortened season.

If everything goes right for this group in 2020, then what you’ll see is more consistency than we saw during their erratic starts last seasons (primarily Kikuchi and Sheffield). This would be a huge building block in figuring out who the starters are for the long term; even the two starters who are on one-year contracts could figure into the franchise’s plan since neither of them are over 30. If Walker and Graveman can stay healthy while pitching at a decent level, then the Mariners could be in really good shape for now and the future.

If the consistency issues from last season rear their ugly heads again, leaving Gonzalez as the best starter by miles, than this 60-game season will be a wash due to how short it is. There will be some new game film for the guys to work with during the off-season, but it would be hard to lose hope about a talented group of young pitchers in such a short year.


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