Oklahoma City Thunder guard Russell Westbrook, who agreed to a new five-year extension on Friday worth morth than $200 million, at the team’s media day earlier this week. (Sue Ogrocki/Associated Press)

There is no player in the NBA more resolute in his desire to do things his way, and on his terms, than Russell Westbrook. Few would argue that after the way Westbrook dominated the league last season, becoming the first player in more than a half-century to average a triple-double on his way to being named the NBA’s most valuable player.

But no one can argue it after Friday, when Westbrook committed the rest of his prime to the Oklahoma City by agreeing to a five-year contract extension in excess of $200 million . . . on the birthday of Kevin Durant, his longtime co-star with the Thunder who left as a free agent last summer. The timing is hardly coincidence.

This is a monumental day for the people here, and for the Thunder as a whole. As recently as three or four months ago, the future of the Thunder was exceedingly uncertain. Many around the league openly wondered if Westbrook, who turns 29 in November, was going to commit the rest of his prime to staying with a franchise that had no clear path to being a contender — and, if he wouldn’t, would that lead to the Thunder having to consider the possibility of trading Westbrook sometime this summer to avoid losing him for nothing, as was the case with Durant.

That, however, was before General Manager Sam Presti pulled off two offseason coups — snagging Paul George hours before free agency began for Victor Oladipo and Domantas Sabonis, then landing Carmelo Anthony hours before training camp began for Enes Kanter, Doug McDermott and a second-round pick.

Suddenly, the Thunder is a contender again. And now Westbrook’s commitment has ensured that the Thunder will be a relevant team for years to come — instead of potentially having Westbrook, George and Anthony all leave as free agents next summer.

But Westbrook signing with the Thunder also does something else: throw what was expected to be an even crazier offseason next season than this one into serious flux.

The star-studded list of players who could be available next summer — beginning with LeBron James and including George, Anthony, Durant, Chris Paul, DeMarcus Cousins, Isaiah Thomas and DeAndre Jordan — is the kind of list of available players one would normally only see in a video game. And with the strong possibility looming that the Los Angeles Lakers — with Magic Johnson as lead recruiter — will have enough cap room to sign a pair of max free agents, the speculation has already begun about what would happen.

Westbrook’s decision, however, undoubtedly increases the chances of George sticking around in Oklahoma City. While there’s no secret he’s interested in going to Los Angeles, George was perfectly happy being in Indianapolis when the Pacers were at the top of the Eastern Conference every year. If the Thunder are in a similar position this season, as expected, the star forward could stick around.

Anthony also seems more certain today to lock into his option for next season, which would guarantee him about $28 million — far more than he’d likely get entering his age-34 season on the open market, and with an ever-shrinking amount of cap space around the league. Durant, meanwhile, is extremely unlikely to leave Golden State, while the Houston Rockets would theoretically be the front-runners to keep Paul to play alongside James Harden in their backcourt.

Some around the league had been openly wondering if, say, Westbrook, George and James would all try to go to the Lakers, or if some equally eye-popping formation of stars would take place. All of that was predicated, however, on Westbrook doing what seemed like the logical thing at the time: waiting until next July to see where his new Oklahoma City co-stars, George and Anthony, decided to do, and making his own decision on his future then.

There was no added benefit to him signing his new deal with the Thunder now — he isn’t getting an extra dime by agreeing to sign an extension now as opposed to signing as a free agent next summer, and he leaves himself in a position where he could be left on an island if those two do decide their futures are better served playing elsewhere.

But Westbrook has never played by any rules other than his own. It’s been true since he was a raw combo guard coming out of UCLA that Presti took a chance on with the fourth pick in the 2008 NBA draft, and many thought would never develop into a point guard. It was true last year, when he ran roughshod over the league in a way few have.

And it was true Friday, when he not only signed the equivalent of a lifetime extension with the Thunder but did so on Durant’s birthday.

It was the ultimate example of Westbrook doing things his way, and on his terms. Now that he’s done so, that will be the way things are around the Thunder for years to come.