Mariners might finally trade Luis Castillo originally appeared on The Sporting News. Add The Sporting News as a Preferred Source by clicking here.

Luis Castillo has already had some frustrations this season for the Seattle Mariners.

And while the M's haven't looked to trade away starting pitching in recent season, they might actually have more than enough surplus right now to deal Castillo.

He's not the pitcher he once was, but if Castillo was on the block before this summer's deadline, he'd attract interest.

Given that the rest of the Mariners' rotation is younger with more promise, Castillo would be the logical guy to move on from.

"Seattle's most seasoned arm has turned things around after going three turns through a piggyback with Bryce Miller, which manifested after Miller's return from the IL gave the club six healthy starters," MLB.com's Daniel Kramer wrote as part of a new article on Sunday. "The Mariners have had extreme trepidation to deal from their rotation in years past and probably will have pause again come July. But if they were to move on from one, Castillo is the clearest, though he does come with a $24.15 million price tag for this year and next."

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As Kramer mentions, Castillo has the kind of contract that could require the Mariners to eat some of the cash to facilitate a deal.

Seattle also won't rush a trade like this. Because of the potential for pitcher injuries, they sort of have to stand firm in case someone gets injured in the meantime. If the depth suddenly goes away, there's a lot less motivation to trade Castillo.

But as far as players on the Mariners' major league roster, Castillo would make much more sense to trade compared to pretty much anyone else.

As the calendar approaches the trade deadline, his name could certainly find its way into some rumors.