Yankees starting pitcher Masahiro Tanaka delivers a pitch against the...

Yankees starting pitcher Masahiro Tanaka delivers a pitch against the Minnesota Twins during the first inning of an MLB baseball game at Yankee Stadium on Monday, April 23, 2018. Credit: Kathleen Malone-Van Dyke

The nightmare fuel that probably has kept Brian Cashman awake on some nights this season has nothing to do with Giancarlo Stanton’s dizzying strikeout totals or the perplexing case of Brandon Drury’s blurred vision.

Those are blips on the Yankees’ radar. Temporary issues that won’t linger.

The really scary stuff — the kind that could derail a team’s title hopes, regardless of their firepower — is rooted in Cashman’s starting rotation, which remained status quo this offseason after Masahiro Tanaka decided to stay put and the GM brought back CC Sabathia on a one-year, $10-million deal.

Based on last year’s overachievement, it was a calculated risk, and one without sufficient insurance stashed in the Yankees’ farm system. There’s not much of a safety net in the Bronx when it comes to that department, which is why Tanaka’s start Monday night against the Twins felt so crucial on April 23 — as will Sonny Gray’s turn Wednesday night.

Tanaka, dethroned by Luis Severino as the Yankees’ true ace, needed to stop performing as if he has only a bit part in this rotation. At worst, Cashman had him penciled in as the 1-A below Severino, not as the back-end starter he has resembled in thrashings by the Red Sox and Marlins.

In that sense, what Tanaka did to the Twins during the competitive portion of Monday’s 14-1 blowout by the Yankees was an encouraging sign. This is who Tanaka is supposed to be.

After opening the game by walking Brian Dozier, Tanaka stayed in control pretty much to the end of his 6 2⁄3-inning stint. He gave up only three hits — two of them singles — and a lone run.

“The fastball command was there tonight,” Tanaka said through his interpreter. “I think it was there more than any other game this season. Because of that, I was able to effectively use the other pitches.”

Tanaka retired 14 of 15 after Dozier’s leadoff walk, never letting the Twins crack the 3-0 lead he was handed in the first inning. With Tanaka cruising, the Yankees kept piling on, adding another homer from Miguel Andujar in the second and a 435-foot blast by Stanton in the fifth. After that, the rout was on.

The Yankees are constructed to bully opposing teams — to land the first punch and continue delivering haymakers. But once they get the pitching straightened out — beyond Severino, anyway — they have a chance to become the juggernaut everyone anticipated.

Entering Monday’s game, the Yankees’ rotation ranked eighth in the American League in ERA (4.49) and batting average (.243). The starters were ninth in WHIP (1.30). We know it’s still April, but that’s not championship material.

Tanaka took the mound with a 6.45 ERA and walked off with a 5.28, so we remain in a small-sample-size zone here. But for the sake of Aaron Boone’s sanity, better to get the malfunctioning parts of this rotation fixed sooner rather than later.

It also was helpful that Boone could keep most of his bullpen holstered, just as he was able to do with the previous two winning starts from Severino (seven innings) and Jordan Montgomery (six). Next up is Sabathia, followed by the increasingly worrisome Gray.

“The bullpen is one of the overwhelming strengths of this club, but you’ve got to be able to protect those guys,” Boone said. “The best way to do that is with quality starting pitching.”

If Tanaka could self-correct his way through some April turbulence, maybe Gray will be capable of a quickie reboot as well. After all, the Twins are in town only through Thursday. It gets much harder after that.

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