Luis Castillo thought he might be a Yankee and is showing what they missed out on

The Yankees have seen Luis Castillo three times in the past four weeks, once with Cincinnati and now twice with Seattle, his new team. It’s been impossible to watch all three of those matchups against New York and not wonder what his presence at the top of the Yankees’ rotation could have meant for the team’s title chances come October.

Outside of a mistake pitch to Kyle Higashioka at the end of the second matchup, which the Yankees catcher hit for a two-run home run, Castillo has looked unhittable against New York. He threw a combined 21 2/3 innings in those three games and allowed just 10 hits and nine walks and racked up 23 strikeouts, including eight shutout innings Tuesday night. In Castillo’s duel against Gerrit Cole, the Mariners won 1-0 in 13 innings.

Castillo’s pitch mix and command make him one of the best starting pitchers in the league. He has stuff that separates the aces from the rest.

“I wasn’t the manager here during the vintage Félix Hernández days, but looking at Félix when he was coming through in his heyday, that’s what it reminded me of,” Mariners manager Scott Servais said last week after a Castillo start. “He’s a No. 1 type of starter. He wants the ball. He can go deep in games. He can do all of those things with the pitches he has.”

The Yankees wanted Castillo. Castillo knew the Yankees wanted him, so much so that he envisioned himself in pinstripes, as he told reporters at Yankee Stadium last week after he made his Mariners debut.

“In my mind, yes, because they were one of the teams that were very interested in me,” Castillo said when asked if he thought he might wind up with the Yankees. “I’m here with the Mariners now, and I have to keep moving forward and take this team as far as I can.”

The price for Seattle to land the best pitcher on the trade market was significant. The Mariners traded away their two best prospects, including shortstop Noelvi Marte, No. 12 on Keith Law’s prospect rankings, and Edwin Arroyo, another shortstop who made Law’s honorable mentions for his top-60 prospect list and was ranked third in the Mariners’ system. Levi Stoudt, a starting pitcher who was Seattle’s No. 5 prospect, was also included in the deal.

The New York Post’s Joel Sherman reported that the Yankees told the Reds their No. 1 prospect, shortstop Anthony Volpe, was off-limits in a Castillo deal. A trade centered on shortstop Oswald Peraza, the Yankees’ No. 2 prospect, wasn’t viewed as highly by the Reds as the Mariners’ package, so nothing came of the talks. The Mariners’ deal should certainly be viewed through the lens of their going all in to add Castillo, who by ERA+ standards was 61 percent better than league average with the Reds this season. There’s also this little postseason drought for Seattle that goes back to 2001, so there’s some desperation on the Mariners’ part to end the misery.

Making the playoffs is not a concern for the Yankees, but winning titles is. That hasn’t happened since 2009, and trading for Castillo certainly would’ve put the organization in a better position to achieve that goal. Cole and Castillo at the top of the rotation would have easily given the Yankees one of the best duos in the league, and they undoubtedly would have been a fearsome pairing no team would have wanted to see in the playoffs. Frankie Montas is a fine consolation prize, especially for the moderate cost of landing him, but he’s not Castillo. Not many pitchers are comparable.

“He’s got great stuff, presence, command and a unique arm angle,” Yankees manager Aaron Boone said of Castillo last week. “He’s got a really good fastball that he can get swing-and-miss with. He’s got a wipeout changeup, a good slider.

“He’s a really good pitcher with a lot of weapons, and that kind of unique arm angle that gives him a different look helps that mid- to upper-90s fastball play even a little more.”

Cole and Castillo could have lessened some of the starting rotation concerns the Yankees have. As it stands, the rotation for a division series likely looks like this: Cole, Montas, Nestor Cortes and Luis Severino, who’s on the 60-day injured list with a lat injury. In a best-of-five division series, the Yankees would almost certainly use Cole in a Game 5, so Jameson Taillon would likely be the odd man out if everyone in the rotation were healthy and pitching well (specifically Severino). Cortes has been outstanding for the Yankees, but we’re entering unknown territory for him. His 112 innings are three shy of his career high, a total that came in the minor leagues four years ago. General manager Brian Cashman and Boone have said Cortes’ workload is something the team is closely monitoring.

The miss on Castillo could also explain the reports that the Yankees were trying to add another high-quality starter to go with Montas before the deadline passed. The Yankees were linked to Pablo Lopez of the Marlins and Carlos Rodon of the Giants, but both ended up staying put.

Before Castillo was traded to Seattle, Matt Carpenter, who saw the pitcher for many years as an NL Central foe when he was with the Cardinals, told The Athletic how this year was the best he’s seen him pitch and how he wished Castillo would end up with the Yankees.

That didn’t happen, and now Castillo has showcased up close to the Yankees what he could have added.

(Photo of Luis Castillo: Joe Nicholson / USA Today)