Why Red Sox's strange top prospect trade should actually worry Mariners

As teams on opposite coasts that don't exactly share a rivalry, the Boston Red Sox and Seattle Mariners don't normally have a lot in common. Yet they've both done trades with the Washington Nationals lately, and Boston's could put them ahead in the race for Ketel Marte.

The Red Sox pulled off an interesting deal with the Nationals on Monday, swapping right-handed pitching prospect Luis Perales for left-handed pitching prospect Jake Bennett, who is now ranked by MLB Pipeline as the No. 7 talent in their system. It's rare to see one-for-one prospect swaps like this, and this one seems designed to deepen the Red Sox's supply of MLB-ready arms.

Craig Breslow seems unable to help himself whenever he gets a chance to acquire pitching. It's been a year since he made a huge move for Garrett Crochet, and he has since used the trade market to add Kyle Harrison, Sonny Gray, Johan Oviedo and now Bennett, who has a 2026 ETA after making it to Double-A this season. Throw in fellow prospects Payton Tolle and Connelly Early, and Boston's supply of starters goes about as deep as any team's.

Why Red Sox's strange top prospect trade should actually worry Mariners

As to how all this relates to Marte, Boston and Seattle are two of the teams in the mix to trade for the three-time All-Star. And now, it isn't hard to put two and two together and make the following conclusion: the Red Sox have a lot of what the Arizona Diamondbacks don't have enough of.

It's been out there that Arizona is going to want young starting pitching in a Marte trade, and preferably arms that are at or near the major league level.

The Mariners can match that asking price, but it would require subtracting from their current rotation by dealing, say, George Kirby or Bryce Miller. They have long been reluctant to do such a thing, and that could be a deal-breaker in this case. A Logan Evans or an Emerson Hancock isn't going to move the needle for a star like Marte, and none of Seattle's top pitching prospects — i.e., Kade Anderson, Jurrangelo Cijntje and Ryan Sloan — is MLB-ready yet.

For what it's worth, Ken Rosenthal of The Athletic reported Monday that Arizona could consider moving Marte for prospects that it could trade to a third team to get what it wants. But that would be a lot less straightforward than making a deal with the Red Sox for one or more of their prized arms.

To wit, a package consisting of both Tolle and Early could be enough to get Marte. The Red Sox also have an outfield surplus they can pull from to entice the D-backs, including by dangling oft-mentioned trade chip Jarren Duran.

Given all this, perhaps it's a bit of mercy that the Mariners seem a lot more focused on Brendan Donovan than they are on Marte. Though Donovan is not the better player of the two, at least he offers a luxury the Mariners don't have versus the Red Sox in the Marte sweepstakes: a battle they can easily win.