MLB insider pitches Mariners-Red Sox trade involving former ROY candidate

There are two things that are very certain this offseason. The first is that the Seattle Mariners desperately need offense. The second absolute is that the Mariners boast one of the best and deepest group of starting pitchers in all of baseball.

With those two distinctions, a lot of people, fans and insiders, are going to predict Jerry Dipoto capitalizing on the pitching depth in exchange for offense. Though that may seem like a plausible idea on the surface, Dipoto has stated that trading any of Seattle's starting five would be "Plan Z."

We can't blame Dipoto at all. The most valuable thing in baseball is young, controllable starting pitching, and the Mariners have been about as good as it gets in developing it. It has become their MO at this point — try and scratch across a couple of runs, let the starting pitching get you through six or seven innings, and turn it over to the bullpen.

Despite the emphasis that Dipoto and the organization have placed on pitching, it isn't a ridiculous thought that trading pitching for offense would be the quickest and easiest way to build a competent offense. Imagine what someone like Logan Gilbert, fresh off a top-six Cy young voting finish, could net you. What about a few years of Bryan Woo or Bryce Miller for dirt cheap? These are all things that Dipoto has to consider, even if it isn't his preferred method of improving the offense.

Mariners Rumors: MLB insider proposes Tristaon Casas-for-Bryan Woo swap

During his time on "Foul Territory," Rosenthal pitched the idea that Boston use Casas as trade bait to help a team in need of offense. That lines up perfectly with Seattle. However, a one-for-one swap of Woo for Casas doesn't really make sense for the Mariners.

Casas fits what the Mariners need: young, cheap, and left-handed power. Casas is still in pre-arbitration and won't start getting expensive for a few years. The 24-year-old has put together a few solid seasons, slashing .250/.357/.473 with 42 home runs in 222 games. He has a career 125 wRC+ and his left-handed power swing would play well in Seattle. On the flip side, the Mariners already have a cheap first baseman, Luke Raley, that they don't need to surrender any assets for.

This is where the deal falls apart. Trading Woo (who might have the most upside in this whole rotation), could be catastrophic for Dipoto. Woo is cheap, and though he had some injury scares in 2024, he was still able to work through 121 1/2 innings, setting a career high. His 1.0 BB/9 was thanks in part to an elite fastball that he continuously threw right by hitters. His 7.5 K/9 leaves a lot to be desired, but shows that the development of an average off-speed pitch could catapult Woo into Cy Young status. That's how good he is.

It may be true that Dipoto would need to deal from the starting pitching depth to acquire truly elite offensive talent; Casas just isn't that guy right now. Maybe there are other pieces that could make the deal work, but this isn't worth executing "Plan Z" for.