Salk: 5 questions about the Mariners’ elite 5-man rotation

Sorry to be sappy, but the words “pitchers and catchers” get me every time. Like many, I was born into loving baseball and watching it is among my earliest and most fond memories. I also hate the winter weather, the cold and the rain, so those two magical words also symbolize the return of the sun and the end of the dreary dark season.

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But the excitement about pitchers and catchers takes on a specific meaning with the Seattle, where we are blessed with five of the best starters (and one of the best catchers) in baseball. While the play of stars like Julio Rodríguez will certainly dictate how far this team can go, none of it is possible without the foundation of starting pitching.

This may well be the best rotation in baseball, and it is the driving force behind any reasonable projection that puts this team in the playoffs.

In honor of their greatness, here are five questions about the best five-man rotation in baseball.

1. Can Seattle Mariners starters lead MLB in innings again?

Essentially, this could be re-framed as “Are they lucky or did they crack the code?” The Mariners’ starters threw nearly 940 innings last season, leading baseball for the second straight year. Even more impressive, they did so by throwing deeper into games than they had in 2023 (5.8 innings per start, up from 5.6), and by using the same five starters for 149 of the 162 games. Throw in 12 starts from true sixth starter Emerson Hancock, and you were left with just one spot start all season. That is insane.

Or is it?

The rotation went consistently deep into games, but no pitcher ever threw more than 106 pitches in any one start. Amazingly, the Mariners had just 20 games all season in which the starter threw 100+ pitches – that was 14th in baseball and below the league average.

Mariners pitchers went deep into games because they were economical with their pitches, not because they were overused or overburdened. Is that more sustainable? Who knows. Pitching injuries confound even the brightest minds in the game. But it’s nice to know that the regularity of their success has been repeated, which gives me some hope.

Because they throw strikes, I do believe Seattle’s rotation can lead baseball in innings again. The question is whether that can come from just five or six pitchers again, and that is impossible to answer.

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2. Who is the Seattle Mariners’ opening day starter?

“The Rock” Luis Castillo has taken the rock to begin each of the last two seasons, and it’s certainly possible that will be the case again on March 27 when the M’s and A’s start the year at T-Mobile Park. He is, after all, the most experienced and highly-paid pitcher of the group. Generally, managers are loathe to rock the boat when they don’t need to, so naming Castillo as the opening day starter is the safest and easiest option.

But this is also an opportunity for Dan Wilson to put his stamp on the team. This is his first opening day as manager and he may value other types of incentives and rewards for his players. Maybe he wants to reward Logan Gilbert as the lone 2024 All-Star of the group? Maybe he thinks it would motivate one of the others? Or maybe, as Brock Huard suggested, it could be a signal to Logan in particular that Seattle should be his permanent home. There have been rumors that he might be the toughest of the group to sign to an extension, but maybe being recognized as the staff ace could change that.

3. Who will take the next step?

As good as this rotation has been, it’s not impossible that it gets even better this year. A pitcher’s prime is generally considered to be ages 26-31. Only Castillo is on the tail end of that range (he’s 32), while Bryan Woo just turned 25. There is no reason to believe Bryce Miller (26), George Kirby (27) and Gilbert (28 in May) can’t improve on their 2024 success. Taking the next step might mean something different for each of them.

For Logan and Kirby, that is competing for and/or winning a Cy Young award. Both (but especially Gilbert) have shown that they are top-of-the-rotation pitchers. But can they be the top of the top? There are lots of No. 1 pitchers in the league, but very few are true, certified aces. With a few years under their belts, both are in that unique zone where their stuff is at its peak and they have learned how to pitch in the majors. This is where the best prove they are exactly that.

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For Miller and Woo, a step forward would be improving their innings and consistency. The two young guys actually led the group in ERA last season but were fourth and fifth in both innings and pitches per start. Getting deeper into more games would provide an extra lift for the bullpen and possibly help the veteran starters ease their outings.

For Castillo, it’s a little different. He is still striking out batters at a prodigious rate, but he allowed more walks and home runs than any of his compatriots. At 32, his stuff isn’t likely to improve and it will be all he can do just to maintain it. This is when the great ones learn how to pitch with less – they use their mind and guile to compensate for their declining velocity. His average fastball has dropped from 97 mph in 2022 to 95.6 mph in 2024. That is more than enough power to succeed, especially with his secondary arsenal, but he’ll need to adjust as that number continues to drop.

4. Who has a new pitch?

It’s always something. Gilbert’s cutter and Miller’s splitter stole the show last year, and my guess is we’ll see a few additions or alterations to arsenals this year as well. And the safest bet is on Miller. It looks like he has been working on a cutter of his own this offseason. I love that for him since cutters can be a way of inducing soft contact and getting deeper into games. If it is as good as his other pitches, this will be a great chance for him to get better.

5. Can they improve on the road?

For all the positives this rotation offers, the one caveat is that they get to pitch half of their games in the friendly confines of T-Mobile Park. Just as that is a challenge for Mariners hitters to overcome, it is an incredible boon for the pitchers. But on the flip side, these splits (courtesy of Luke Arkins of Mariners Consigliere) of the M’s starters’ opposing slugging on fly balls are alarming:

• Luis Castillo: .786 home, .867 away
• George Kirby: .431 home, .856 away
• Logan Gilbert: .629 home, .955 away
• Bryan Woo: .545 home, .509 away
• Bryce Miller: .368 home, .769 away

(MLB average slugging on fly balls vs. starting pitchers: .802)

Whoa. Gilbert, Kirby and Miller really benefited from fly balls being caught at home. Couple that with what we now know about the park’s effect on strikeouts, and you can see why pitchers love it here. But if we have these numbers, so do they. And my hope is they can adjust their strategy on the road to limit fly balls and induce more on the ground. I’ll certainly be watching to see if they can even these out.

For more, listen to the middle segment of the podcast below from Tuesday’s edition of Brock and Salk on Seattle Sports.

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