The stove is getting hot for the Seattle Mariners.

The first two days of MLB Winter Meetings in Dallas were quiet on the trade and free agent front for the Mariners. The biggest news for te team was that they were confirmed to be pursuing Roki Sasaki.

But while Seattle tries to bring Sasaki into the organization, the team’s veteran starting pitcher might be on his way out.

It was reported on Day 1 of Winter Meetings by Adam Jude and Ryan Divish of the Seattle Times that the Mariners and Boston Red Sox reportedly engaged in trade conversations involving Luis Castillo going to Boston for first baseman Triston Casas early in the offseason.

Per the report, those talks fell through in the exploratory stages and hadn’t resumed. That fell in line with Seattle President of Baseball Operations Jerry Dipoto’s comments on Sept. 28 when he said trading a pitcher was “plan z” for the club.

The Red Sox acquired starting pitcher Garrett Crochet from the Chicago White Sox in return for several prospects on Wednesday. But a report from MLB Network’s Jon Morosi said that Boston was still working to acquire one of Mariners starting pitchers.

A report soon after from Jude used the word “persistent” to describe Boston’s pursuit of one of Seattle’s starters and confirmed that the two sides had been engaging in trade conversations.

A trade between the two respective East and West Coast teams isn’t imminent. But the original proposal of Casas for Castillo makes the most sense.

Dipoto has said that the team is searching for a starting second and third baseman and a first baseman to pair with Luke Raley. The Red Sox were in need of starting pitchers. The swap works for both clubs.

Castillo is the oldest and highest-earning starting pitcher on the Mariners’ roster. He’ll be 32 years-old on Dec. 12 and is set to make $24.15 million in 2025. He finished the year with a 3.64 ERA and 175 strikeouts in 175.1 innings pitched across 30 starts. He also made his third career All-Star Game in 2023.

Castillo does have a no-trade clause he can exercise to nix a deal. But if Seattle does have to move a starter, Castillo is the most likely candidate due to his age and money.