Over the weekend, The Boston Globe’s Alex Speier reported that the Mariners were willing to entertain offers on Luis Castillo. Trade chatter has picked up in the few days since then. Daniel Kramer of MLB.com writes that the M’s have received a higher volume of trade calls since Max Fried agreed to an eight-year deal with the Yankees on Tuesday.

Castillo, who turns 32 today, seems to be the one member of the Seattle rotation who’ll be available. President of baseball operations Jerry Dipoto has continuously shot down the idea of trading from his young quartet of Logan Gilbert, George Kirby, Bryan Woo and Bryce Miller. The M’s reportedly rebuffed the Red Sox when Boston floated a framework of Triston Casas for one of their young starters.

Jon Morosi of the MLB Network suggested yesterday that the Red Sox and Mariners remained in conversations about Seattle’s starting pitching. Boston is probably unwilling to give up Casas for Castillo, however. To that end, Speier relayed last night that a source informed him there was no traction on a deal that would involve those two players.

While Castillo is a less appealing target than Seattle’s controllable arms, he should have positive trade value in his own right. He’s coming off another productive season. Castillo started 30 times and worked to a 3.64 earned run average over 175 1/3 innings. He punched out 24.3% of batters faced against a solid 6.5% walk percentage.

That’s a slight step back from his typical production, as he combined for a 3.47 ERA with a 26% strikeout rate over the preceding three seasons. Even if this wasn’t his best year, Castillo looks the part of a mid-rotation starter. He has topped 150 innings in each of the last six full seasons. Castillo’s fastball sits in the 95-96 MPH range. He still has a better than average strikeout and walk profile.

The differentiators between Castillo and his rotation mates are his contract and age. He’s signed for three more seasons at $22.75MM annually. The deal contains a ’28 vesting option valued at $25MM if Castillo reaches 180 innings in 2027 and finishes that year healthy. There’s some protection for the team in the event he suffers a significant arm injury. If Castillo requires surgery to repair the UCL in his throwing elbow and misses more than 130 days, there’d be a conditional $5MM club option for 2028.

Leaving the options aside, the contract has $68.25MM in guarantees for his age 32-34 seasons. That’s probably a little less than what he’d make if he were a free agent this offseason. Castillo is more consistent than Yusei Kikuchi, who got $63MM going into his age-34 season. He has similar numbers to Nathan Eovaldi, who just inked a $75MM deal for ages 35-37.

One complicating factor: Castillo’s deal includes a full no-trade clause through the end of next season. The trade protection goes away at the end of the year (though he would receive a $1MM assignment bonus if he’s traded after 2025). Kramer writes that the Mariners have informed the righty that they’re fielding more interest. The report doesn’t shed any light to which teams, if any, Castillo would approve a trade.

If he’s amenable to moving, the Mariners should be able to offload most or all of the contract while netting a legitimate return. A potential cornerstone bat like Casas is a stretch, but it’s reasonable to expect some kind of immediate lineup help. It’d also open budgetary space for the front office to add to the offense in free agency. Ryan Divish and Adam Jude of the Seattle Times have reported that the M’s are working with around $15-20MM in payroll room; Kramer suggests the same in today’s report at MLB.com. Pushing that closer to $40MM would open a lot more opportunities for Dipoto and his staff to strengthen the corner infield.

It would be a notable hit to their rotation. Much is made of Seattle’s young starting pitching, deservedly so. The talent at the top does obscure a general lack of depth beyond their excellent front five, however. Emerson Hancock hasn’t shown much at the MLB level despite his billing as a former sixth overall pick. He has a 4.71 ERA with a 14.3% strikeout rate in 15 big league starts.

Hancock and soft-tossing lefty Jhonathan Diaz are the top depth options on the 40-man roster. The Mariners didn’t need to rely on either pitcher much in 2024. Their front five combined for all but 13 starts all season. Even if they bring back their entire rotation, it’s unlikely they’ll be quite so fortunate from an injury perspective. Trading Castillo would almost certainly necessitate a rotation acquisition, either in that trade or via subsequent free agent pickup. One need only look at how quickly the Marlins’ starting pitching has been depleted over the past two seasons as an example of the risk for teams in believing they have a rotation surplus. That’s no doubt a factor in Seattle’s general unwillingness to listen on their younger arms.