Mariners insider pours cold water over fans' hopes for a major rotation shakeup

The Seattle Mariners are one of the only teams in MLB that entered the offseason with a perfectly intact and perfectly functional starting rotation. It's typically a good idea not to mess with such things. But then again, there's lots of time in the offseason for idle hands to get restless.

What if the Mariners chose not to leave good enough alone? What if they made a trade for a No. 1, such as Tarik Skubal? Or at least, what if they moved Luis Castillo and freed up an extra $24.15 million for their offseason budget?

Yet such thoughts always felt like the work of idle hands, and now the illusion is pretty much kaput. The gist of the latest from Adam Jude of The Seattle Times breaks down like so: No, the Mariners are not trading for Skubal, and no, they're not trading Castillo either.

Mariners insider pours cold water over fans' hopes for a major rotation shakeup

Starting with Skubal, the dream of bringing the former Seattle University standout back to the Pacific Northwest had already gone up in smoke in mid-November. And while ESPN's Buster Olney reports that the Detroit Tigers are engaging with other teams, Jude writes that the "industry consensus" is that the two-time Cy Young Award winner is unlikely to go anywhere.

Even if it was otherwise, Jude says "it’s even unlikelier that the Mariners would be willing to stomach the sort of package it would take to bring Skubal back to Seattle."

If this is surprising, it is only to the extent that the Mariners are one of very few teams in MLB with the prospect capital to match Detroit's astronomic price tag for Skubal. Yet even if they did, they'd only be getting back a one-year rental. Skubal is set for free agency after 2026, and is likely to have a market value somewhere in the $400 million range.

If the Mariners were badly in need of a No. 1 starter, maybe they'd be willing to go all-in on Skubal anyway. But when you have Bryan Woo, Logan Gilbert, George Kirby, Bryce Miller and Castillo on your side, a No. 1 looks a lot less like a need and more of a mere want.

As for Castillo, he's certainly the most sensible trade chip of those five in the abstract. He was the team's ace and Opening Day starter as recently as last year, but his modest 104 ERA+ for the last two seasons captures his decline into mediocrity. Once again in the abstract, the $24.15 million the Mariners owe him in 2026 could be better spent elsewhere.

Unlike last year, however, Jude writes that the Mariners "do not intend to shop Castillo on the trade market."

This isn't surprising either, to be honest. Decline or no decline, Castillo has remained a valuable source of innings, averaging 184 per season since 2023. And given that he was the only one of their starting five who didn't miss time with an injury in 2025, the Mariners may have a newfound appreciation for just how valuable it can be to have a tried-and-true workhorse around.

There may also be the question of Castillo's trade value, or lack thereof. Even though his no-trade clause has expired, the Mariners wouldn't have leverage to ask for much if they did try to shop Castillo. Heck, when we tried our hand at cooking up fair trades, all we could do was pitch packages that were either bad contract swaps or centered on low-level prospects. Once you get into territory like that, it's better the devil you know than the devil you don't.

All told, Jude's reporting is the latest in a line of developments that has made it harder to imagine the Mariners shaking things up too much. They really seem intent on running it back with the same team that got to within eight outs of the World Series in October.