On Opening Day, the Washington Nationals — and their fans — thought that the team’s biggest problem was a coronavirus outbreak that sidelined nine Nats. Come on, what could make the Nats lose more sleep than covid-19?

Try a 6.15 ERA for their Big Three starting pitchers. And cameras showing Stephen Strasburg rubbing his shoulder between innings while sitting in a dugout tunnel Tuesday night in St. Louis as he gave up eight runs.

At least there is a vaccine for the virus now. But how do you keep $585 million worth of pitchers — with Patrick Corbin signed through 2024 and Strasburg through 2026 — healthy and productive for years and years to come?

Now the virus looks like a six-game April blip on the radar screen with that 1-5 start barely worth a gray hair. Instead, the Nats may have bigger worries, emphasis on “may” with a side helping of “probably not.”

By May, this trio could look a great deal like the 2019 World Series-winning version of themselves, though a couple of years older. If they get back in regular rotation rhythm with their veteran arms stretched out in warm weather, the Nats may look like contented contenders.

But for now, anyone who is not concerned about the Big Three isn’t watching. The Nats need ‘em all. They are the present. Strasburg and Corbin are the future, too.

On Opening Day, ace Max Scherzer gave up a homer on the first pitch of the season and allowed four homers to the first 10 Braves he faced. In his first five glamorous Nationals years, Scherzer’s ERA was 2.74. Last year, in 12 starts, it was 3.74. Was that a tip-off to age?

In his only start since his pandemic-proximity purgatory, Corbin, who gave up more hits than any major league pitcher last year, had poor command, allowed six runs and got just 13 outs. Corbin repeatedly missed his spots by a few ball-widths — so far off the plate that no one chases or so much over the middle that everyone clobbers. Some pitches missed by much more.

Corbin’s velocity, the action on his pitches and the poor reaction of hitters when he did hit his spots were normal Corbin. Maybe quarantine just hurt his routine. But he hasn’t been the 2018-19 version of himself (3.20 ERA) since all his double-duty work in the Nats’ title run. Until the old Corbin returns, that brave risk-taking for the sake of World Series rings will hang over his head.

On Tuesday, with all the pandemic players (except Jon Lester) back, Strasburg gave up three homers, threw fastballs from 89 to 93 mph, didn’t get a swing-and-miss until his 51st pitch and was shown kneading the trapezius muscle area between his neck and shoulder.

Now that many are in Full Fret, let’s explain why MLB makes us all crazy, even as it fascinates us. You would think these data points might tempt the Nats to start their home stand Friday with Cassandra Bobblehead Night.

The Nats’ concerns are real, but they’re not simple.

Consider Mad Max. After that gopher-ball beginning, in his 10 subsequent innings, he has allowed only one run (on a lost-in-the-sun fly) and just five base runners while fanning 11. Max also battled Clayton Kershaw ably for six innings at Dodger Stadium. All in all, he has been adequate (3.75 ERA) vs. the two best National League lineups.

The eye test says Max, at 36, is still very good.

Strasburg made just two starts last season before having wrist surgery for carpal tunnel syndrome. Yet he built up his pitch-count load past 90 in Florida and hardly could have looked better in his first start, keeping the Braves scoreless on one hit with eight strikeouts in six innings.

So are we to believe that Strasburg, five days later, has somehow evaporated?

Or is it more likely that he just had the infamous early-season “dead arm” start or a muscle spasm in his trapezius — in the neck, not the dangerous areas of the shoulder, such as the labrum. Also, he’s still building arm strength after 18 months of minimal action.

“I’ve had bad [games] like this before in my career,” Strasburg said afterward. “It’s a long season. It’s April. We’ve had kind of a very strange start to the season.

“Whatever you guys [in the media] want the narrative to be, that’s your call,” Strasburg said, almost pleasantly. “I’m just going to give it everything I’ve got every start.”

On Wednesday, as usual on the day after a start, Strasburg threw in the outfield in St. Louis. Maybe exhale, for now. But this is Strasburg, so never pretend you can see too far into his future. What makes him great — a snapping of wrist, elbow and shoulder that involves enormous torque — is also what leaves him vulnerable over a 32-start season.

Under contract until he’s 38, Strasburg wants to last long enough to earn it. To do so, he will have to pitch effectively at lower velocity with excellent command, like one of his models, the late Roy Halladay. Expect him to dot his fastball, making it cut both ways, at less than max effort with his big weapons being his wipeout curve and change-up.

That version of Strasburg — wiser and more accepting — knows “I’ll have five or six starts that are very bad.”

Nats fans hope they get to fret right through 2026.

Of the Big Three, Corbin is probably the closest to a quandary. Perhaps no high-priced modern starter has put himself at risk to the degree Corbin did for the sake of a ring. What will the final price be for those five relief games, plus his starts? And who’s to say it wasn’t worth it, regardless of the answer?

Right now, if it were not for the struggles of the team’s strongest trio, there are so many other bright — or at least acceptable — signs that the Nats’ 3-6 start may be a fake-out. Josh Bell, Kyle Schwarber, Josh Harrison and closer Brad Hand all look like they are adequate to their roles — or a bit more.

And there may be a significant surprise — and support for the Big Three — in the person of Joe Ross.

The Nats have waited for a mature, polished version of the right-hander, now 28, since he was a hot prospect at 22. He has needed elbow surgery, lacked confidence in his stuff at times and been a nibbler. Then he opted out of last season. It has been a long, patient time.

Would he always be just sinker-slider and a showcase change-up that shouldn’t be allowed over the plate? Would he add something — a fine cutter to play off his sinker, both hard but bending in opposite directions?

It’s just two starts, but those pieces may have fallen in place. When you two-hit the Dodgers for five scoreless innings, then blank the Cardinals for six, as Ross did in a 6-0 win Wednesday, attacking with a high percentage of strikes, using four pitches, it’s time to wonder: What have we here?

The narrative of this season’s Nats has barely begun. New characters are arriving. But the old familiar protagonists are still, by far, the most important. We may already know the name of this book: “The Big Three Mystery.”