The Mariners aren't necessarily inclined to trade the All-Star righty, but that doesn't mean that other teams aren't calling.

Interest in Castillo increased significantly after the New York Yankees signed free-agent lefty Max Fried to an eight-year, $218 million contract, a Mariners source said. Castillo, 32, is owed less than one third that amount – $68.25 million over the next three years.

The Mariners have an opportunity to use some of their excellent starting pitching depth to improve the offense but the team has doubts.