Hours after dropping a stunning Garrett Crochet trade on the league early Wednesday afternoon, MLB Network’s Jon Morosi reports Red Sox are working to acquire another starting pitcher from the well-armed Seattle Mariners.

The Red Sox previously offered first baseman Triston Casas to the Mariners in an attempt to pry Bryce Miller or Bryan Woo from the west-coast club, but were unsuccessful.

Unless the Red Sox offer additional position players or high-level prospects, the Mariners are highly unlikely to part with any of their four young starters. Exchanging Casas for the more veteran Luis Castillo makes sense for both clubs, but Alex Speier of the Boston Globe reported that when he asked a source if there were any legs to a Castillo/Casas swap, he received a “straightforward ‘No.'”