A moment like the one Kevin Durant gave the NBA on Monday, when he announced he was leaving the Oklahoma City Thunder for the Golden State Warriors, doesn’t happen because of one thing, because of one event. Instead, a moment like this happens because of a series of events – many of which seem to pass by unnoticed when they happen – that add up to the kind of crescendo the NBA experienced when Durant’s letter on the Players’ Tribune was posted for the world to see.

The path leading to Durant’s departure began inside a boardroom high above Manhattan’s Central Park five years ago, and with the NBA and the National Basketball Players Association’s negotiations to come up with a new collective bargaining agreement and end the owners’ lockout of the players in 2011.

No, the NBA is not completely at fault for Durant leaving Oklahoma City, as some have said in the wake of his decision. But some of the agreements that took place as those talks were wrapping up in the wee hours of the morning on Nov. 26, 2011, set in motion some of the events that led to Durant’s decision.

The league’s owners were smarting from the formation of the Miami Heat’s trio of LeBron James, Dwyane Wade and Chris Bosh the year before, and instituted a far more punitive luxury tax to try and prevent teams from hoarding stars the way the Heat had. But while the tax did wind up helping to lead to the Heat’s decision to waive Mike Miller to save money — angering the players, including James – it also had an impact on a group of budding young stars in Oklahoma City.

Oklahoma City was in the midst of its ascension to the top of the league, one centered around a quartet of young players: Durant, Russell Westbrook, James Harden and Serge Ibaka. That Thunder team went all the way to the NBA Finals in 2012, beating the San Antonio Spurs along the way and pushing the Heat before eventually losing to Miami in five games. It looked like the start of a new dynasty in the West, and the team that would keep facing James and the Heat in the finals year after year.

That’s not how things worked out. The Thunder, spooked by that luxury tax, decided to trade Harden instead of paying it when the two sides squabbled over a contract extension in the fall of 2012. Oklahoma City shocked the league by trading Harden to Houston and getting what turned out to be an underwhelming package of players in return (though it did eventually net the Thunder its current starting center, Steven Adams).

What the Thunder didn’t anticipate at the time was that the NBA was about to get a massive influx of cash from the league’s next television contract – the same one sending shock waves through the system this summer by increasing the salary cap by roughly 35 percent. Oklahoma City may have avoided the luxury tax altogether, and paid it no more than once or twice, if it had kept Harden because of the overall inflation in salaries now under way in the NBA.

Still, it seemed the Thunder had the kind of team capable of winning championships anyway, with a nucleus of Durant, Westbrook and Ibaka. But then the Thunder suffered an injury to each of its stars the next three seasons – a torn meniscus for Westbrook in 2013, a calf injury for Ibaka in 2014 and a broken foot for Durant in 2015 – that prevented Oklahoma City from having a healthy team at the end of the postseason in any of them.

Oklahoma Thunder forward Kevin Durant was named the NBA's 2013-14 most valuable player. He gave an emotional speech during the award ceremony. (The Washington Post)

Meanwhile, another decision from those 2011 lockout negotiations loomed large last summer. When the league’s owners and players union hammered out their agreement, the ability to give players a full five-year extension a year before free agency was eliminated. Last year, if the Thunder had been able to offer Durant a five-year extension, it would’ve had the opportunity to test Durant’s intentions. If he’d said no to extending his contract, then Oklahoma City potentially have sought out a trade – as painful as that might’ve been – to try and get something for him.

But because the Thunder couldn’t, it had to wait and see what happened with Durant. And midway through the Western Conference finals this spring, it appeared playing that waiting game was the right call for Oklahoma City. The Thunder had taken a three-games-to-one lead over Golden State in that series, blowing the 73-win Warriors off the floor in Games 3 and 4 in Oklahoma City, and moving the Thunder to within one victory of a return to the finals four years after its first trip, and the rematch Durant and Westbrook desperately wanted with LeBron James.

Then came Golden State’s stunning comeback in the series, including a performance in Game 6 that, it could easily be argued, the Warriors couldn’t duplicate if they replayed the game a thousand times. Klay Thompson had the game of his life, scoring 41 points and hitting 11 three-pointers, and he and Stephen Curry combined for 72 points to win that game before Curry had 36 points in Game 7 to send the Thunder home for the summer.

Even then, it looked like Durant would be returning to Oklahoma City. The Warriors had slayed their demon, and the assumption was they’d go on to win a second straight title, cap off the greatest season in NBA history and make it difficult – if not impossible – for Durant to join them on the heels of that.

James and the Cleveland Cavaliers, however, had other ideas. And after the Warriors’ Draymond Green was suspended for Game 5 of the finals, the Cavaliers began their own comeback from down three games to one to bring a title to Cleveland for the first time in 52 years. Suddenly, yet another thing that was supposed to keep Durant from making this decision had fallen away.

Then came the final nail in the Thunder’s coffin, with the massive rise in the salary cap. This wasn’t something that could realistically have been negotiated back in 2011 – at the time, the consensus was the league’s new television deal, set to kick in this coming season, would likely double in size. Instead, it basically tripled — to $24 billion over nine years — setting up a scenario where the salary cap would explode this summer when the new money began pouring in.

When the new television deal came to be, the NBA knew problems could be on the horizon, and went to the players association to try and negotiate a “smoothing” proposal, to allow the money to more gradually come into the system and avoid any sudden salary cap spikes. The union, however, declined to do so, feeling it was better for the money to simply come in as it was supposed to.

And it has this summer, to the tune of a $94 million salary cap for the 2016-17 season – up from $70 million last year, and enough of a jump that the five teams who met with Durant (the Warriors, Spurs, Los Angeles Clippers, Boston Celtics and Heat) could all sign Durant without having to completely gut their teams to do so. That includes Golden State even having the good fortune, if you can call it that, of Stephen Curry’s recurring ankle troubles leading to him signing a four-year, $44 million contract in 2012 – a deal that’s now become the best value contract in the entire NBA.

It was an unprecedented scenario, one that allowed Durant to be pitched the possibility to play on a Warriors team with Curry, Thompson, Green and Andre Iguodala. It was a possibility that proved too good for him to pass up.

And so Durant stated Monday that he was leaving the Midwest for the Bay Area, sending shockwaves through the NBA that won’t stop reverberating anytime soon. But the genesis of that decision didn’t come this past weekend, in his three days of meetings with those six teams. Instead, it came from a series of events over the past few years, culminating in Monday’s stunning announcement.

Some of the key statistics that show how this year's Warriors team measures up to one of the all-time great NBA teams, the '96 Chicago Bulls. (Thomas Johnson, Osman Malik/The Washington Post)