When might Mariners bring Kade Anderson up to big leagues?

This story was excerpted from Daniel Kramer's Mariners Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

SEATTLE -- Kade Anderson’s path to the big leagues this season was always going to hinge on how the Mariners’ roster looked in the aftermath of the Trade Deadline.

And now, that avenue appears much clearer.

With Luis Castillo gone and the club operating with a standard five-man rotation, Anderson has ascended to No. 6 on the depth chart. And the front office plans to meet this week to map out a plan for the left-handed uber prospect to impact the big league roster for its hopeful playoff push.

That said, they will not transition him into a relief role for the foreseeable future.

“We're not going to put Kade in the bullpen,” Mariners president of baseball operations Jerry Dipoto said. “He's the best starting pitcher in the Minor Leagues. I think he leads the Minor Leagues in everything, not [just] the Texas League, but [all of] the Minor Leagues. And he is trending in every way you can.”

Indeed, among 235 qualified pitchers in the Minors, Anderson ranks first in strikeout-to-walk rate (36.4%), strikeout rate (40.5%) and FIP (1.88), second in ERA (1.20) and OPS against (.408).

He's now the No. 5 prospect in all of baseball, per MLB Pipeline, and is No. 1 within the Mariners' system.

Essentially, this boils down to the Mariners wanting to not disrupt what’s been working so well for Anderson, the No. 3 overall pick in last year’s MLB Draft.

But perhaps even more so, they also want to ensure he remains on track to reach his workload target for the full season.

Anderson has accumulated 82 1/3 innings across 16 starts this season, all at Double-A Arkansas. He threw 119 last year at LSU in the regular season then another 16 in the College World Series, where he won Most Outstanding Player honors.

Conceivably, that 135-inning range is what the Mariners are targeting. And it’d put him on track to make an even bigger jump in 2027 -- and for a permanent stay in the big league rotation at some point next year.

Shortening him up would compromise that outlook.

“For us to put him in a bullpen right now would be irresponsible for his future development,” Dipoto said. “There is going to come a time where we get to a juncture in the season where we're no longer concerned. Right now, he is the next starter up. And for us, that is an important element, especially now with Luis no longer here.”

So, how could Anderson’s contributions down the 2026 stretch look?

The cleanest path would be around Sept. 1, when rosters expand from 26 to 28. If the Mariners remain in the hunt, and the rest of their starting five remain healthy, they could inject Anderson to the rotation and go to a six-man.

They also have only three off-days in September, and it’s possible that extra rest for everyone could be a factor -- as it has been at multiple points since the club last went to a piggyback on June 19.

The Dodgers did this last year, to gear up their starters for a lengthy run that extended into November.

“There are five traditional starters on the Major League club, and having a guy like Kade in the background is a really positive thing,” Dipoto said. “So, to shorten him up would not be something we would consider.”

That said, if Anderson is nearer to his workload target by the final month -- which the Mariners haven’t put a firm, or at least public, number on -- they could then consider a different plan.

“We may get into September, if we don't need to tap the extra starter, now we can talk about more creative things,” Dipoto said. “But we're not going to plan on a [reliever] runway. We're more likely to be creative in how we use him as a Major Leaguer, once he gets here.”

There’s a lot to dream on, for not just what Anderson could offer this season, but for way beyond. And it appears his time is nearing.

“There's extra velocity,” Dipoto said. “The precision has come so far, even since the day he signed. He's doing everything we could possibly expect or ask him.”