3 Teams the Mariners Should Be Negotiating With at the MLB Trade Deadline

The Mariners don’t need to spend the next few weeks refreshing the rosters of baseball’s worst teams and hoping to find a miracle worker buried beneath years of club control. They’re best shot at making a deadline splash just might be calling other contenders.

It sounds backward because it is. Buyers are the ones usually raiding sellers, and sellers are supposed to demand prospects and everyone pretends the trade deadline operates through a clean, orderly division between the teams chasing October and the teams that can’t wait for next April.

Quite frankly, this season is a mess. It’s not clean or orderly.

The Mariners have too many starting pitchers and not enough dependable offense. Other contenders have their own lopsided rosters, financial questions and positional surpluses. That creates an opening for Jerry Dipoto to do something more creative than shipping away more prospects for a rental.

Dipoto has already acknowledged the possibility of buyers negotiating with other buyers. It’s uncommon, but Seattle doesn’t need a common solution. It needs a right-handed hitter and another late-inning reliever without stripping even more talent from a farm system. That should put these three teams near the top of Seattle’s call list.

Mariners Should Skip the Sellers and Call These 3 Contenders

1. Chicago Cubs

The Cubs are plucking arms off of waivers like someone trying to finish a sticker book. They’ve spent the season squeezing innings out of claims, depth signings and whichever healthy arms happen to be available. To their credit, it has kind of worked. The Cubs entered the All-Star break at 54-42 despite injuries forcing them to piece together portions of the pitching staff.

But teams with serious postseason expectations eventually need more than waiver-wire luck. The Cubs could use a legitimate starting pitcher, and the Mariners happen to have one they are reportedly willing to discuss, with Luis Castillo believed to be the most likely candidate.

Seattle should immediately ask what it would take to get Seiya Suzuki in the deal. There are some complications with that. Suzuki has a no-trade clause, and the Cubs are not going to hand over an established hitter with 15 home runs and a .811 OPS.

Seiya Suzuki gives the Cubs the lead as they look to sweep the Orioles! pic.twitter.com/lZZ1AxXnOG
— Talkin' Baseball (@TalkinBaseball_) July 9, 2026

2. Baltimore Orioles

We have been talking about the Orioles needing pitching for so long that it feels more like a yearly tradition. Baltimore develops position players. They stockpile young hitters. Then they reach the deadline and search for someone trustworthy enough to start a postseason game.

Nothing has changed. Well, actually, they went out and acquired Shane Baz who stumbled through the first couple of months before looking like a real pitcher again in his last three starts.

The Orioles and Mariners are natural trade partners because their roster construction problems point directly at each other. Seattle has starting pitching to spare. Baltimore has the type of right-handed offense the Mariners need.

Castillo would give the Orioles an experienced starter. Seattle, meanwhile, should make Taylor Ward the starting point of the conversation.

Ward was acquired by Baltimore during the offseason and is scheduled to reach free agency after 2026. Baltimore would have to decide whether it plans to extend him, keep him for a postseason run or use him to acquire the pitching it has been chasing for years. The Mariners should help them make that decision.

Castillo for Ward straight up would not necessarily balance the financial or baseball value, so Seattle should push for an additional arm. It does not have to be Baltimore’s best pitching prospect. A controllable reliever or upper-level pitcher with legitimate bullpen upside could make it more appealing.

Taylor Ward leadoff bomb in his return to Anaheimpic.twitter.com/M2BQ7hRrql
— Underdog MLB (@UnderdogMLB) June 23, 2026

Ward would address the right-handed-hitting need. Another arm would help protect the bullpen. Baltimore would finally acquire the starter it keeps searching for every summer. Enough said.

3. San Diego Padres

We are allowed to be a little selfish here. Who doesn’t want to see what Jerry Dipoto and A.J. Preller could cook up after a few years apart?

Their previous trades gave Seattle Ty France, Andrés Muñoz and Matt Brash. That’s an absurd amount of long-term value to emerge from a pair of dealing sprees. Adam Frazier brought that winning streak to a screeching halt. But nobody bats 1.000 when working trades.

The larger point remains: These two guys are willing to get weird. And this season, Seattle and San Diego may need a weird trade. Both teams reached the All-Star break hovering around .500, close enough to the postseason race that surrendering would be premature but flawed enough that standing still would be irresponsible.

The Padres desperately need starting pitching. Their rotation has been battered by injuries and inconsistency, and even MLB’s analysis of their deadline outlook identified a mid-rotation starter as a likely target.

San Diego also has exactly what the Mariners should want in high-end relief pitching.

The Padres have built a premium bullpen, and Preller has repeatedly added late-inning arms even when the roster already appeared deep. Mason Miller is the biggest name, but that’s not necessary. More like Adrian Morejon (7-2, 3.42 ERA, 50 IP, 58 K) or Yuki Matsui (0-1, 2.73 ERA, 33 IP, 35 K).

Either way, both teams need to find the right lane.

Perhaps that means a larger deal involving Castillo and one of San Diego’s controllable relievers. Perhaps the Padres prefer a younger Seattle starter and are willing to expand the return. Who knows? The possibilities are exactly why Dipoto should make the call.

The matches are sitting there. Dipoto only needs to start negotiating.

Add us as a preferred source on Google