Stop right there. Put on the brakes. Pour ice water over your head. This is no time to fall into spring-is-here silliness just because baseball is back. Not this year. Get a grip on reality. Because the Nationals better.

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Have you noticed whom the Nationals face at 1:05 p.m.? Jacob deGrom, the best pitcher in the majors last year. His 1.70 ERA was the 13th best in 100 years.

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After this three-game New York Mets series, the Nats host the Philadelphia Phillies with Bryce Harper next week, then go on the road — to play the Mets and Phillies all over again. In the first two weeks, that’s 11 straight against key National League East rivals.

Talk about a quick reality check. The Nats, considered to be anywhere from the eighth- to 10th-best team in the majors and often placed with the Phillies atop the division, are under the gun right from the gun. Of course, so is everybody else in the NL East. At least the Nats are essentially healthy. Atlanta’s rotation and the Mets’ lineup are not.

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In a scary, urgent way, the Nats’ opener captures the theme of their entire season. Is this talented but radically restructured roster, with a dozen players who barely know each other, ready to perform at near-peak efficiency immediately so it can cope with a season that might be semi-buried and demoralized — or glorious and flying — before the end of May?

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Eight Nats are entirely new this offseason — 32 percent of the roster. Another three didn’t arrive from the minors last year until May. Two more Nats left, then returned as free agents. And a couple, including obscure give-him-a-nice-hand Jake Noll, are just filling in for dinged vets Howie Kendrick and Michael A. Taylor.

So, who hands out name tags? Is this crew ready for instant rough weather?

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Have you seen the Nationals’ schedule? I mean, have you really looked at it the way players themselves do — spotting the key showdowns against the toughest foes in their own division, as well as series against the handful of truly excellent teams in the rest of the sport? Have you imagined the difficult road trips cross-country and tried to imagine the narrative of a season that faces these tests?

If you’re an ardent baseball fan and have scanned the Nats’ schedule, you may be ecstatic at the prospect of watching, by far, the most quality matchups against top opponents that you may ever get to see. Goodbye, boring NL Least.

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But if you’re just a fan of the Nats, you may need to crawl under the bed and peek out once a week to see whether your team has survived another crisis or if this extremely important transitional year is already skidding all over the road.

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Last year, the Nats weren’t ready to play after a lax fundamentals-optional, create-your-own-schedule training camp. They started 11-16 and fell six games behind the Atlanta Braves in a blink. It took them a month of digging to nose back into first place, briefly, by late May. But piece after piece — first the bullpen, then an injured lineup and finally a failing rotation — all flunked their stress tests badly. If anything like that recurs, the Nats may think a divisional stampede passed them.

The issue isn’t just that the first two weeks of the season will be blighted with hurlers named deGrom and Noah Syndergaard, Aaron Nola and Jake Arrieta. By May 29, the Nats will have played the Mets (13 times), Phillies (eight) and defending division champion Braves (two) a total of 23 times — nearly half of their entire season total of 57 games against these top division foes.

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They will also face the cream of the rest of the NL — the Los Angeles Dodgers, Chicago Cubs, St. Louis Cardinals, Milwaukee Brewers and Colorado Rockies, all projected to be in the top dozen teams in the majors by ESPN — in 17 other games.

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Of the Nats’ first 56 games, 40 are against the teams they need to beat the most. In a sense they are all “double games” because, by late September, when division standings and wild-card spots are being determined, it’s almost certain that these are the teams you will devoutly wish you had whipped.

So, hey, just kick back and enjoy that Opening Day flyover that Scherzer says gives him such a boost. It’s a law that the Opening Day score is never an omen.

But very soon the Nats better have their belts cinched. Such early-season intensity is not a normal baseball state of mind — long season, the cream will rise, never panic. But this NL East, with four contenders, is not a normal division.

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Remember, both Davey Johnson and Dusty Baker won division titles after dedicating spring training to this speech: “Fast start. Did everybody get that memo: FAST START wins it!” So far, Martinez has mentioned no general themes. Just “win today’s game.” That is both profoundly true and potentially infuriating if repeated 162 times in response to the entire range of (major league) human experience.

Many act as though the notion of four winning teams in one division is unique and such a logjam means that nobody wins 90 games. Also, the wild cards come from other easier divisions. This seems so logical. But it’s bunk.

Such a remarkable division has never existed in baseball since . . . last year. In the NL Central, the Brewers, Cubs, Cardinals and Pittsburgh Pirates won 96, 95, 88 and 82 while the Cincinnati Reds lost 95. The Cubs were the first wild card. The Cardinals were in the wild-card hunt until the last week. If I had to predict this season and wanted to enjoy myself but also avoid safe choices, I’d say that the Nats and Phillies win 96 and 95 games (or vice versa) while the Braves win 88, the Mets 82 and the Miami Marlins 67.

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The Nats are a fascinating collection because they are capable of an unusually wide range of outcomes — anywhere from 78 to 98 wins (with 88 my commercial cop-out midpoint). Why? Their rotation, if healthy, could be powerful and their lineup multiskilled with enough power but energizing speed.

But if Scherzer, who turns 35 this season, or Stephen Strasburg, who has lost a bit of jump on his fastball, or Corbin, who throws a stressful 50 percent breaking balls, has a poor or injured season, then the Nats’ whole theory of the game — “We’re always built on starting pitching,” General Manager Mike Rizzo said — gets a wrench thrown in it. Every element in that promising rotation is to some degree an unstable isotope.

“Every year is unique to itself. You learn to understand everybody’s personality,” said Scherzer, mentioning that now is the time for a club “to bind.”

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“The Lerners and Mike Rizzo did their job [in the offseason],” he added. “Now it’s time for us to go out and do our job.”

Check the schedule: starting immediately.