The New York Mets made the offseason’s biggest splash by signing star right fielder Juan Soto to a record-setting deal, but most of their other moves have lacked excitement, fortifying their depth and the fringes of the roster, including in the rotation.

While offseason signings Frankie Montas, Clay Holmes and Griffin Canning raise the floor of their starting staff, the Mets still crave a top-of-the-rotation pitcher, which is currently led by Kodai Senga. If president of baseball operations David Stearns prefers to avoid paying top dollar for pitchers in their 30s, there’s a trade he could make for one who will come at a bargain salary, according to ESPN’s Buster Olney.

“(Luis Castillo) makes so much sense for me, for the Mets,” Olney said on Wednesday’s “Baseball Tonight” podcast. “You look at the Mets, and how it feels like they need to do a lot more with this starting pitching. They’ve got this large group of position player prospects. And now, to me is the time where maybe you can talk to the Mariners about one of those guys.”

Castillo would be an excellent addition. But at Olney’s price?

“Mark Vientos. And I don’t know what the Mets’ response to that would be because Vientos looked so good down the stretch for a couple months,” Olney said. “But that, to me would be one potential ask for the Mariners — like I could see him being a guy that Mariners would be excited about because he’d plug and play, he’d be in the big leagues right away.”

Report Alden Gonzalez said, “I like that one,” though he thinks the Boston Red Sox offering first baseman Tristan Cosas would be better.

Vientos’ breakout — after some yo-yo’ing to start his career — transformed the Mets’ lineup. He posted a 135 OPS+ in the regular season thanks to 27 home runs, 77 RBIs and a .266/.322/.837 line. And he came up even bigger in the postseason with a .327/.362/.638 line and a team-high five home runs and 14 RBIs.

The 25-year-old has cemented himself as an important middle-of-the-lineup piece, though he’s not much more than that. His defense at third base is suspect, and he’s a very slow runner, forcing a move to first base (or even designated hitter) in the next couple of years. Would that reality entice Stearns to take advantage of his breakout season now for an ace like Castillo? If he did, it would mean holes at first and third base and newfound aggressiveness in the free agent market for players like Alex Bregman (third base) and Pete Alonso or Christian Walker (first base).

Still, in Olney’s trade, the Mets would acquire an ace for at least the next three years at $22.75 million annually, per Cot’s Contracts, which is well below market value. Lefty Max Fried, who is younger and better, got eight years and $218 million from the New York Yankees this offseason.

Castillo has pitched at least 160 innings in five seasons, and he has a career 3.56 ERA. Last year, the second-worst of his career, he posted a 3.64 ERA and 1.17 WHIP across 175 1/3 innings. He had 175 strikeouts.

Is the 32-year-old worth Vientos?