The Washington Post's Adam Kilgore breaks down Bryce Harper's road to being named the National League’s Most Valuable Player. (Monica Akhtar/The Washington Post)

In the past 30 years, just two professional athletes in Washington have been named the MVP of their leagues: Alex Ovechkin of the Capitals and now, on Thursday, Bryce Harper of the Nationals. The parallels between them — and the expensive conundrum they posed for their teams — are almost identical.

The Great Eight won his first MVP after the 2007-08 season when he was 22 . Harper won for 2015, when he was 22 . The Capitals responded with a 13-year contract extension for Ovechkin at the highest price in NHL history: $124 million. That’s a scary amount of loot that still holds the record in the often-revenue-pinched NHL.

Many questioned both the length and the amount of that deal. When Ovechkin had injuries — and even two entire “off” seasons — that contract looked as if it might be an albatross. Instead, Ovechkin, now in his 11th season, came back to win his third Hart Trophy — hockey’s MVP — in 2012-13 and was runner-up last season.

His goal Thursday night was his 484th, which made him the highest-scoring Russian in NHL history. After this season, he will play four more in Washington. Once, that seemed ominous. Could he adapt his game — to age, a new coach, a new position or system? The past four years have shown he can do all those things. As a result, he probably will be of enormous value, even if he isn’t a Hart contender, until the last of those 13 seasons.

Ovechkin’s deal may be the smartest, most franchise-defining decision in Ted Leonsis’s tenure as owner. Though the $9.5 million annual salary is still considered high for hockey, it created a Rock the Red culture that has filled Verizon Center for years.

Those sellouts have continued despite playoff disappointments. Why? The central reason may be that fans know that they can invest emotionally in the entire career of one of the best who ever lived. Imagine the state of the fan base if the Capitals had the spring flameouts every season but without Ovechkin? Would fans have shown the same tolerance? They nagged Ovi for two years. But they never left.

An extroverted, emotional, spontaneous superstar with charisma — and perhaps a whiff of controversy, too — is simply a different kind of animal than any other creature in his sport. How often does a city get a man-monster in hockey who scores bushels of goals and blows up foes or a superstar ballplayer with light-tower-power and all five tools who’s also a “clown question, bro” quote machine?

The Washington list, since 1901: Walter “Big Train” Johnson, Slingin’ Sammy Baugh, Ovechkin. With due respect, no Riggos or Big E’s need apply.

After four full major league seasons of evaluation, Harper will probably — no, don’t say certainly — spend the next 10 years joining that class. Will it be in D.C.?

There’s a big difference between the Caps signing Ovechkin and the Nats trying to ink Harper. Ovi’s rookie deal was up; he represented himself. So there was a deadline and also good will.

In contrast, Harper’s a Nat through 2018. But a deal would need to be done long before that. His agent, Scott Boras, may say many things, but his track record speaks loudest: He uses a team to bargain but tests the market to set dollar records.

What is Harper actually worth? Through age 22, the player he most resembles statistically is Frank Robinson: both right fielders, both combative, sometimes reckless and injured. And both at times booed or misunderstood.

The rest of the 10 Most-Similar-to Harper-at-22 include Mickey Mantle, Hank Aaron, Ken Griffey Jr. and Miguel Cabrera, all of whom are — or almost certainly will be — in the Hall of Fame.

Once such an athlete and personality has identified himself so young — as Ovechkin and now Harper have — how can you let him get away? Even though you know the risks of a contract that may end up feeling like it lasts until eternity.

There are four other names on that list of 10-most-comparable-to-Harper. And those should concern the Lerner family as they decide whether to offer an extension that might reach $425 million for 12 or more years.

Those names represent three types of outcomes. Tony Conigliaro, beaned and almost blinded, symbolizes injury. Cesar Cedeno, supposedly the Willie Mays of the 1970s, represents the inexplicable career slide. He batted .320 twice, hit about 25 homers and stole around 55 bases every year and won Gold Gloves in center field. Then, at 26, he became almost ordinary.

The third category of Harper comps is the trickiest. The Nats already control Harper at ages 23, 24 and 25. So they only need to figure out what he’s worth after 2018. Orlando Cepeda, who’s in the Hall of Fame, and Andruw Jones, who had an excellent career, performed well from age 26 onward with a career wins-above-replacement of about 25 after age 25. That’s very nice. But that’s not worth anything like $400 million for 13 years when you already have the first three years locked in at reasonable prices.

If Harper is as productive as Robinson, Mantle, Griffey, Aaron or Cabrera, then letting him get away might be the worst decision in Nats history, no matter the price. If he’s Conigliaro or Cedeno, it’s a disaster. Even if he’s Cepeda or Jones, it’s not worth it.

See how easy it is to own a big league team?

I’ve made an obsessive hobby of studying career arcs in baseball. To me, the picture of Harper is clear. Four years is enough to set a minimum baseline. Assume his whole career mirrors 2012 to 2015 — a modest estimate. With reasonable health, Harper would be around the 50th-best hitter of modern times, similar in value to Harmon Killebrew or Eddie Mathews.

If you give Harper more benefit of the doubt and combine his 2014 and 2015 seasons — one a worst-case injured year, the other a max season he may seldom achieve again — then you get a .307 batting average, .417 on-base percentage and .558 slugging percentage with an OPS+ of 163. That’s similar to Albert Pujols, Stan Musial and Jimmie Foxx.

What if 2015 is his norm? Or what if he gets a little better? Sorry, I’m not going there. He’s not Ted Williams until he does 2015 about 15 more times. (Get back to those crunches, Bryce.)

In baseball, once a hitter does it — whatever “it” is — then he probably will do it again someday. If he does it at 22, he will come fairly close several more times. Look for the list of power-plus-patience players with 42 homers and 124 walks at 22.

The list: Harper.

Previous youngest: Babe Ruth, at 25.

For Harper and the Nats, this is the day to celebrate Washington’s first baseball MVP in 90 years. But it’s also a day to contemplate the future — and not just 2016, 2017 and 2018.

Can you say “Ovechkin deal?”

For more by Thomas Boswell, visit washingtonpost.com/boswell.