SEATTLE -- In the wake of his upcoming season-ending surgery, where do James Paxton and the Mariners go from here?

The news delivered from manager Scott Servais on Tuesday was a blow for both Big Maple, who was determined to overcome the many injuries that have kept him from pitching an entire season, and the Mariners, who planned to lean heavily on the left-hander to catapult them into the final stages of their rebuild.

Paxton didn’t just represent an arm that would accumulate upwards of 170 innings -- vital for a pitching staff that beyond Marco Gonzales and Yusei Kikuchi is still very young -- he’s also been one of the best left-handed starters in the American League when healthy over the past four years.

“Certainly, it’s a blow,” Servais said. “We were super excited when we ended up re-signing Pax, because you’re adding a top-end, this is a top-end starter, a top-of-your-rotation guy. And certainly nothing against our other guys, but they just don't have the experience and the track record Pax is accumulated over his time in the big leagues. So it's disappointing.”

Paxton’s void puts the Mariners in a more precarious spot with than they would have liked at such an early stage of the season. Here’s why, and here’s where they can go from here:

Who are the rotation reinforcements?
Logan Gilbert, MLB Pipeline’s No. 29 prospect, is coming soon, but not for at least another month, if not longer. The Mariners have earmarked the bulk of Gilbert’s innings for the second half because they intend for the 23-year-old to finish the season in the big league rotation and not be shut down early.

“We have young pitching in the Minor Leagues as well that we'd like,” Servais said. “Understanding those guys didn't pitch all last year, we have to be very careful on how we build those guys up, and when we possibly expose them to the Major League level because the intensity does rise at the big league level.”

For now, Nick Margevicius will hold Paxton’s spot. The lefty made his first turn in place of Big Maple on Tuesday, and gave up six runs over three-plus innings. Margevicius was always going to make big league starts sooner than later in 2021, but with their fill-in now filling in, who’s next in line until Gilbert is up?

Ljay Newsome took Paxton’s spot on the 26-man roster and is serving as the long man in the bullpen for now. He was stretched out to as many as four-inning starts in Spring Training, and he made four starts in 2020, when he assumed Taijuan Walker’s spot after Seattle traded Walker to Toronto. Newsome had a 5.68 ERA in those outings, and the Mariners lost all four.

Beyond Newsome, Robert Dugger and Jimmy Yacaobinis are the lone starters at the alternate training site and would be next in line. But seeing any of these three making starts would hinge on some considerable health issues in the coming weeks.

“I don't get too far down the road because as we all know pitching staffs change,” Servais said. “They evolve over the course of the year based on injuries, performance, how some guys are doing and things like that. But I do feel good about our depth -- certainly not as good as I felt we started the season, because some of those guys are moving into more prevalent roles.”

The Trade Deadline strategy
Contending for a postseason spot in August and September is what general manager Jerry Dipoto has said would be the barometer for a successful 2021. Yet if the Mariners aren’t where they hope to be by mid-July and Paxton was in the midst of a big bounce back, he would have represented their most valuable trade chip to contending teams -- particularly given the low-stakes commitment of his one-year, $8.5 million deal that could have reached $10 million with performance bonuses.

The Mariners had similar approach last season when signing a recovering Walker to a one-year deal then trading him to Toronto after he was off to a stellar start. That brought back outfielder Alberto Rodriguez, who is still a few years away but ranks very highly among international prospects.

And of course, the blockbuster with San Diego that netted Ty France, Taylor Trammell, Luis Torrens and Andrés Muñoz is already showing big returns. But that came at the cost of Austin Nola, Austin Adams and Dan Altavilla, all of whom the Padres viewed as key contributors and were included on their postseason roster.

Dipoto has said that the Mariners will be active in free agency when the time is right, and this offseason represents a fitting time in the context of the state of the rebuild and which free agents will be available, such as Javier Báez, Carlos Correa and Trevor Story.

But the Deadline represents a much more creative way to bolster the roster and typically at a more economical cost -- and Dipoto has never lacked creativity. But without his biggest chip, the front office might have to become even more imaginative to shape the long-term roster come July.