REPORT: Red Sox To Pull Off Blockbuster Trade For $108 Million Mariners Ace

The Boston Red Sox are in one of the strongest positions in the league, boasting both significant talent at the major league level and the top-ranked farm system, even after trading prospects for Garrett Crochet. This robust pipeline enables them to pursue blockbuster trades to strengthen their roster further. One area they are likely to target is the starting rotation. Zachary Rymer of Bleacher Report recently predicted that the Red Sox might execute another major trade this offseason, potentially acquiring Seattle Mariners pitcher Luis Castillo.

“Castillo’s fastball has been one of the most effective pitches in baseball over the past two seasons,” Rymer noted. “He’s a workhorse, having made at least 30 starts in five of his eight major league seasons. Even with $72.5 million left on his contract, Castillo’s value could be enough to fetch a quality bat for Seattle, or even a standout one if the Mariners are willing to cover part of his salary.”

If Seattle agrees to absorb a significant portion of Castillo’s remaining contract, a trade framework becomes straightforward. A swap involving Red Sox infielder Triston Casas could be mutually beneficial, with additional prospects exchanged depending on the financial terms.

Boston has considered shifting Rafael Devers to first base, which would overlap with Casas, and they are actively exploring third-base options. Trading Casas for an ace like Castillo aligns with Boston’s priorities. Meanwhile, Seattle, in need of offensive upgrades at the corner infield spots, could benefit greatly from acquiring a 24-year-old talent like Casas.