SEATTLE -- The Mariners¡¯ Hot Stove season started to simmer late Wednesday evening as most of the team¡¯s front office personnel chartered back to Seattle from Dallas-Fort Worth International Airport following the Winter Meetings.

Yet notably absent from that group was president of baseball operations Jerry Dipoto, who remained in Texas as buzz swirled about trade interest from other teams in Luis Castillo, who all of a sudden looks even more desirable given what starting pitching is costing on the free-agent and trade markets.

Indeed, multiple sources told MLB.com that the Mariners have been taking a higher volume of calls on ¡°La Piedra¡± in the wake of Max Fried signing with the Yankees for $218 million and Garrett Crochet being traded from the White Sox in exchange for four of Boston¡¯s top prospects at the Meetings.

And ...

¡°They¡¯re not hanging up,¡± a source with knowledge of the situation told MLB.com.

Castillo, who has a no-trade clause through next season that he¡¯d have to waive, has been informed that the Mariners have fielded increased interest from other teams, a source said.

The Mariners have been unwavering in their intent to keep their starting rotation intact, which Dipoto said on Monday has ¡°resulted in a lot fewer phone calls than we've usually fielded.¡± But that¡¯s never stopped them from doing due diligence when teams reach out.

The Red Sox, even after acquiring Crochet, have engaged the Mariners for one of their starters, MLB.com¡¯s Jon Paul Morosi reported on Wednesday. Boston reached out earlier this offseason on a deal centered around first base slugger Triston Casas but reportedly wanted Bryce Miller or Bryan Woo in return, which was a non-starter.

Other teams seeking starters -- and possess MLB-ready infield talent that the Mariners desire -- include the Cubs, Phillies, Orioles and Yankees, the latter of whom Seattle out-bid to acquire Castillo at the 2022 Trade Deadline.

Among his rotation peers of Miller, Woo, Logan Gilbert and George Kirby, Castillo has long seemed like the most logical to be moved given that he¡¯s the oldest of that group (he turned 32 on Thursday) and by far the most expensive (with three years and $73 million remaining).

Those reasons were also why the industry belief has been that he wouldn¡¯t net nearly as much on the trade market this offseason as the other four, but sources have suggested that the overall starting pitching market demands have been extreme.

When considering the recent signings of Luis Severino (two years, $67 million with the A¡¯s) and Nathan Eovaldi (three years and $75 million with the Rangers), Castillo -- who is arguably a better pitcher -- and his contract could seem far more palatable. It¡¯s also not in the megadeal range of Fried or Blake Snell (five years, $182 million with the Dodgers).

Castillo¡¯s market -- or any tradeable starter, from the Mariners and across the league -- could become even stronger once Corbin Burnes, this year¡¯s top free-agent starter, signs.

¡°As long as there are players that are available for money, no players and no talent in return, but just cash, there's always going to be some disparity,¡± Dipoto said this week. ¡°The player who doesn't cost you talent is always going to be more appealing to most teams than the player who cost you talent plus selling. So once that part of the free-agent market starts to dry up or disappear, then teams are usually a little bit different than their behaviors.¡±

Another massive domino is Roki Sasaki, the phenom who was posted by his Japanese club this week and is expected to begin negotiating with MLB teams soon. The Mariners intend to be among his suitors, but so will teams like the Dodgers, Padres, Yankees and Red Sox.

Yet Sasaki¡¯s agent, Joel Wolfe, suggested at the Meetings this week that Sasaki likely won¡¯t sign until the international signing period begins on Jan. 15. That could leave interested clubs in limbo -- and potentially soar Castillo¡¯s value further for those who miss out on Sasaki.

To be clear, the Mariners don¡¯t want to trade Castillo. But with a budget that sources have suggested has only $15-$20 million to work with this offseason, and the clear needs for at least two infield bats, they¡¯re being forced to at least consider it.