Welcome to the suddenly Roaring 2020s.

These are the boom times. With a new collective bargaining agreement in place after last offseason’s lockout, we have entered a new age of spending in baseball. Steve Cohen is leading the charge, but the Steinbrenner Yankees are not far behind and neither are the Phillies and Padres.

Of the eight biggest contracts by total dollars dished out in free agency (so excluding extensions) in Major League Baseball history, three (Aaron Judge, Trea Turner and Xander Bogaerts) are less than a week old, including the two largest of all time (Judge and Correa, who agreed to a 13-year, $350 million deal Tuesday night with the Giants, The Post’s Jon Heyman confirmed). More than $3 billion has been committed to free agents this offseason — and there are scores of free agents yet to sign. Two offseasons ago, teams handed out about $1.3 billion total to free agents.

Last offseason, the top three contracts (Corey Seager, Kris Bryant and Marcus Semien) totaled $682 million. This offseason, the top three contracts (Judge, Correa and Turner) have totaled $1.01 billion.

Seven players have joined the nine-figure-contract club, and at least two more (Dansby Swanson and Carlos Rodon) are expected to join them. There has never been a better time to be a free agent — a fact seemingly no one saw coming.

The Post’s Jon Heyman, who is as clued in as anyone, ranked this offseason’s crop of free agents in early November and, with the help of an outside expert, predicted how much each would receive. About six weeks after the story was published, the vast majority of players who have signed have beaten the expectations.

The top 15 free agents who have inked deals this offseason have been guaranteed $251.7 million million more than Heyman’s expert predicted. We are not picking on Heyman, whose expert has actually proven more accurate than most.

Take Judge, for example. Here were several of the leading publications’ best forecasts for the deal the superstar would sign:

The Post: nine years, $330 million
MLB Trade Rumors: eight years, $332 million
The Athletic: eight years, $330 million
FanGraphs: nine years, $315 million
FanGraphs crowdsource: eight years, $300 million

Each outlet underestimated the nine-year, $360 million megadeal Judge scored with the Yankees — a pact the Padres may have beaten if Judge wanted to be in San Diego.

We thought Jacob deGrom, an unrivaled ace with a litany of injury red flags, would make $125 million over three years. The fans at FanGraphs, through a crowdsourced opinion, thought he would get $120 million over three seasons. Zero outlets in this sample believed a team would offer deGrom more than three years, and the most generous projection entailed deGrom receiving $141 million.

DeGrom signed a five-year deal with the Rangers worth $185 million.

It is not just the dollar commitments but the years that have astounded. Last offseason, the 10 biggest contracts given out averaged 5.8 years. This offseason, the average has been 7.4 years.

It is not as if this offseason’s crop of players is perfect. There are all sorts of concerns about how a giant (not a Giant) such as Judge will age. There are all sorts of concerns about how players who rely on speed, such as Turner, will adapt into their late 30s. Turner, whose crowdsourced contract estimate was seven years, $210 million, landed a $300 million agreement for 11 years from the Phillies. Because of injuries, Brandon Nimmo has played more than 100 games in a season just twice in seven years. A player whom the crowd pegged as worth $100 million over five seasons is coming back to the Mets for $162 million over eight seasons.

The presence of Cohen surely is playing a role in the extravagance. When the sport’s richest owner took over in late 2020, he promised to turn the Mets into the East Coast Dodgers: a juggernaut that has the resources to import huge free agents and the structure to develop its own prospects. Because the Mets’ farm system is not yet ready, Cohen is spending at an astronomical rate — just like the Dodgers did in the early 2010s, which allowed them to rebuild and replenish on the fly. Cohen has sailed past the highest luxury-tax threshold and will set a new record with a 40-man roster that will cost him more than $400 million. It made Tuesday night’s reports of the Mets’ interest in Correa, presumably to play third base alongside Francisco Lindor, seem not so far-fetched.

After anteing up for Judge, Hal Steinbrenner has won respect from Yankees fans who were skeptical of his willingness to reach into his wallet. The surprising Padres, coming off a run to the NLCS with a starry lineup that helped them draw their most fans since 2004, have kept pace with the spending and brought in Bogaerts for 11 years and $280 million. The Phillies, coming off a thrilling sprint to the World Series, are spending “stupid” money again with deals like Turner’s. The dormant Giants have finally come alive.

Maybe the Phillies’ success last season — having snuck into the postseason as the NL’s sixth seed in an expanded format and reached the World Series — also has something to do with the lavishness, motivating others to push harder for an extra playoff spot. Perhaps the windfalls from Major League Baseball selling its stake in BAMTech to Disney last month — and bringing in $900 million for the streaming technology services group — are trickling down to the free-agency class. Maybe after a new CBA was completed, there are fewer worries about the future of the sport. Or perhaps there are fewer concerns about aging players’ steep declines, as athletes know more about their bodies than ever before.

The “why” is important, but it is less eye-opening than the “what.”

At $3 billion and climbing, the age of baseball excess is here.

Today’s back page

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The extra smile

Cohen, a Mets fan before he was the owner, undoubtedly cares about winning. As the Mets roll out their free-agency treasures — there will be a media session Wednesday involving David Robertson, José Quintana, Brooks Raley and GM Billy Eppler, before Nimmo’s news conference arrives Thursday — the secondary attributes of Mets targets seem to have mattered, too.

In their announcement of the eight-year deal for Nimmo, the Mets did not harp upon a belief the outfielder had turned a corner physically and could remain healthy the rest of his career. Instead, the Mets made clear that Nimmo — whose smile never fades and who has become a fan favorite — is the type of person the Mets want around.

“Brandon has been part of the Mets family since he was drafted over 10 years ago and we are so excited that he and his wife Chelsea decided to remain part of the team,” Cohen said in the release. “Throughout his career, Brandon has contributed so much to the Club both on and off the field. His hustle and personality are a part of what makes this team so special.”

Edwin Diaz, back on a five-year, $102 million deal, recently was given the Ben Epstein/Dan Castellano Good Guy Award by the New York chapter of the Baseball Writers’ Association of America. Diaz brings an upbeat attitude and a chorus of trumpets with the most electric walk-out scene in baseball.

Sure, the Mets wanted a closer who posted an absurd 1.31 ERA last season, but Diaz is a personality both fans and teammates want nearby.

“Edwin has every attribute we look for in a closer,” Eppler said in a statement. “He’s a tremendous competitor, has a burning desire to be the best and possesses the stuff to compete with any hitter in the league. We are thrilled he’ll be anchoring our bullpen moving forward.”

The Mets, whose clubhouse earned a thumbs-down for the 2021 season, clearly still are valuing qualities beyond skill level.

The real MVP?

About a month ago, Jacque Vaughn cut off the question with a smile and a quick retort.

“He’s our MVP, so we’ll keep it that way,” the Nets head coach said when the subject of Kevin Durant being in the early MVP conversation was broached. “That’s good enough for us.”

Can you be possibly the best player in the world and still be underrated?

Durant is quietly — or somewhat quietly, at least, considering all the Kyrie Irving and Ben Simmons headlines that have emerged in the first third of the Nets’ season — putting together what is looking like the second-best season of his career.

The gold standard is his 2013-14 campaign, the only one that ended with an MVP award. Durant, then 25, carried the Thunder into the Western Conference Finals, where they lost in six games to the Spurs. The young Durant did everything — 32 points, 7.4 rebounds, 5.5 assists and 1.3 steals per game while suiting up for all but one regular-season matchup. He shot 50.3 percent from the field, efficient as ever.

Durant is now 34 and on the other side of an Achilles tear — and he somehow has gotten more efficient. He’s shooting 55.9 percent from the field, which would be his best mark ever. After another 30-point game in Monday’s win over the Wizards, he is averaging an even 30 points per game. Durant is up to an absurd 62.9 percent shooting on 2-point field goals; Simmons, who essentially only takes layups, is shooting 61.9 percent on his 2-pointers.

If he stays healthy — which is a large “if” for a player averaging 36.7 minutes per game — Durant is mounting an MVP case while ignoring so much that has gone wrong around him.