3In the final days of September 2024, fans were beginning to look ahead to what could happen in the offseason. Although hopes were alive for the New York Mets, and amazingly reached with a win in game 161 to guarantee a playoff spot, thoughts of “what could be” infiltrated other teams. Specifically, the Seattle Mariners were on the verge of finishing one game from a playoff berth. Their fans suffered many of those same moments of rage as we did at the end of the 2025 regular season.

Even with their quest not yet over with, a tweet came out proposing a 1 for 1 swap for the offseason. The Mets would send them Mark Vientos. In return, New York picks up Luis Castillo.

A well-valued trade at the time, it would have rewarded the Mets with a frontline starting pitcher under team control for several seasons at a reasonable price; $24.15 million per season through 2027 with a vesting option for 2025. The Mariners gain a young power hitter. A year later, it feels like a missed opportunity.

This proposed Mets-Mariners trade reminds us how far Mark Vientos has fallen

There’s a good chance Vientos ends up on the trade block for real this offseason. He can’t play third base. He doesn’t have enough offensive consistency to justify being a first baseman or DH. A more patient team might be willing to let him play every day. The Mets weren’t in a position to let him hit his way out of a season-long funk in 2025. The power drop, that didn’t show up until late in the year, was the biggest injustice to those of us who believed there was very little another team could offer in exchange for his services.

Through October 2024, Vientos proved his fans correct in judging him as far too valuable to give up in a trade. He had more clutch hits in his first postseason than a player with his experience level should ever have. Whatever was wrong with him in 2025 now makes us look foolish for ever believing this proposed trade was too costly for the Mets to seriously consider.

Every trade has at least two sides to tell. Castillo had a predictably solid season. He finished 11-8 with a 3.54 ERA in 32 starts and 180.2 innings. The ERA was 0.01 below his career total of 3.55. Although strikeouts fell to 8.1 K/9, he regularly got the job done. Notably, Castillo went 6+ innings in each of his final four regular season starts. He gave up 1 run in 3 of them. The other featured 6 scoreless in a win over the Kansas City Royals. He’s scheduled to start game two for the Mariners in the ALDS.

Vientos remains a puzzling player for the Mets. His 2024 season couldn’t have been one-and-done. It was too fantastic to just all disappear without explanation. And yet, there is no easy way to explain it.

A Vientos for Castillo swap was never a real trade between the Mets and Mariners, just fans pondering what could help both clubs. Completely out of the question for this coming offseason on the scale it was last year, those of us who weren’t willing to deal Vientos for an obvious Mets missed our opportunity to make an impactful trade on paper.