Minutes after Kevin Durant 's decision to leave the Oklahoma City Thunder was announced, the unleashing of Russell Westbrook's triple-double potential was the first thing on the minds of some rather prescient rival guards.

Portland Trail Blazers guard C.J. McCollum tweeted "Russ about to avg a triple double with 30" complete with two crying emojis. LA Clippers guard Austin Rivers seemed a little more serious about it, tweeting, "On another note....Russ might go Oscar next year. In this era that would be crazy."

But actually averaging a triple-double, though? It seemed like a total long shot.

Betting site Bovada set the over/under for Westbrook's triple-double total at 20.5. Writers everywhere pondered whether Westbrook could do it, with most concluding, "Maybe, but almost assuredly not." In December, ESPN Insider Kevin Pelton's simulation model put Westbrook's chances of averaging a triple-double at 33 percent.

"I never know what's possible, or what's not possible, what people can or can't do. I don't limit myself. I just say 'why not' and continue to play."

Westbrook, who's now averaging 31.7 points, 10.7 rebounds and 10.4 assists per game, always had a different mindset.

"Why not? That's my motto. That's what I believe," he said Tuesday morning before recording triple-double No. 41 to tie Oscar Robertson for the NBA single-season record.

"Some people may play with it and laugh with it, but that's how I really think, what I really believe. I never know what's possible, or what's not possible, what people can or can't do. I don't limit myself. I just say 'why not' and continue to play, and that's my motto and I stand behind it."

With his sixth assist on Friday against the Phoenix Suns, Westbrook has actually done it. He hit the statistical trinity, the hallowed trio of round numbers previously thought to be unattainable in the modern NBA.

He is the first player since Robertson in 1961-62, and only the second ever, to average a triple-double. Average a triple-double.

Let's pause here for a moment to let that sink in.

Russell Westbrook's triple-double chase has rallied Oklahoma City and its team following the painful departure of Kevin Durant. Layne Murdoch Sr./NBAE via Getty Images

For Westbrook, his march on history was all about mental preparation. Thunder general manager Sam Presti recently told ESPN the Magazine's Tim Keown that Westbrook's season was a test of "mental endurance." That preparation began even before Durant made his decision, with Westbrook bracing for the possibility he'd enter the 2016-17 season in a completely different role -- as a solo act.

Westbrook's offseason training carries its own mythos, with his actual regimen mostly unknown. He's one of the most physically gifted players in league history; he's also one of the hardest working. Westbrook's work ethic is something of legend around the Thunder practice facility, with teammates, past and present, raving about his weight-room achievements and never-ending tank of energy on the practice floor.

As Anthony Morrow said February when Westbrook made a jaw-dropping play to seal a win against the Grizzlies: "He'd make that same play in practice."

Westbrook's ability to seemingly defy fatigue mystifies many, but Westbrook himself has always explained it simply: "I decide not to [get tired]." It's not exactly a scientifically sound explanation, but for Westbrook, it's his reality. It's mind over matter. He believes it's his choice how to play, and when he's on the floor, fatigue is just one of the many defenders trying to slow him down.

Flash back to the Thunder's first game of the season, an emotional 103-97 win over the Philadelphia 76ers. It was an exhausting night, one when Westbrook squeezed everything out of his 36 minutes.

As he dressed in the locker room, taking his time to get his yellow hoodie and kilt just right, one staffer joked, "So he's just going to need to do that 81 more times." Westbrook seemed spent, both physically and mentally, but that was only how it appeared. Two nights later he went 45 minutes in an overtime win against the Suns, dropping his first triple-double of the season: 51 points, 13 rebounds, 10 assists.

By Nov. 28, when he posted 27, 17 and 14 against the New York Knicks, he was officially averaging a triple-double for the first time this season. He was asked that night if his numbers were sustainable, and he quickly said, "Winning is sustainable," which seemed like a pithy reply but didn't exactly mean anything. Turns out, though, the numbers were sustainable.

Since then, he has averaged 12.0 assists per game.

By mid-December, Westbrook was already tired of talking about the pursuit.

"Honestly, people with this triple-double thing is kind of getting on my nerves," he said. "People think if I don't get it, it's like a big thing. When I do get it, it's a thing. If I get it, I get it. If I don't, I don't. It is what it is. I really don't care, not for the hundredth time. I don't care. All I care about is winning."

He said that after a loss to the Jazz, which marked the third straight game he failed to record a triple-double. (That's how things went this season -- three games without a triple-double was a drought.)

When he did get asked -- pretty much only after wins -- he had a standard response, almost like a prepared statement or an automatic reply on an email when you're out of the office. Something along the lines of, "I'm just blessed, I compete at a high level each and every night." If you had a word cloud on Westbrook's season, "compete," "high level" and "blessed" would be featured prominently.

Westbrook tried to shield himself from the historical conversation, because he has always been sensitive to the narrative he was a stat-padder or someone interested in individual attention. He tried to redirect everything to the team and winning, but make no mistake: He wanted to set this mark.

He said this week, publicly at least, that averaging a triple-double wasn't a personal goal. But Westbrook is famously competitive, maybe the most competitive athlete in sports, and he wants that MVP, and he wants the history. After he tied Robertson on Tuesday, there was a clear relief and a previously unseen appreciation by Westbrook of what he'd accomplished.

He let himself enjoy it a little bit and, more important, enjoy it in front of people.

Russell Westbrook and Oscar Robertson, forever linked within NBA history. AP Photo/File

Westbrook's season was also a welcome distraction for the organization as it recovered from the shock of Durant leaving. The expectation from most within the franchise expected the cloud of Durant to linger over every game. The nightly narrative would be about what was gone, instead of what remained. But Westbrook changed the conversation, redirecting the focus of fans, teammates and staffers to his achievements. The words "triple-double" became rallying cry in Oklahoma City, and not that Durant was forgotten, but there wasn't any moping around. The arena buzzed on a nightly basis, still loud and still full, all packed in to see what Westbrook might do.

Thunder head coach Billy Donovan was always a believer, all the way back to November, when Westbrook's three averages first ticked over to double-digits.

"Yeah, he could do it. He could do it," Donovan said earlier this season. "I'm not gonna say he is or isn't, because I think the more important thing is Russell is winning, but he's a guy that has great impact on generating assists. He has a great impact on rebounding the basketball, and he can score. So there's certainly a possibility that can happen. Obviously, what he's done at this point in time has been pretty remarkable."

The question most had was if Westbrook could bring down enough rebounds. Last season he averaged 23.5 points, 7.8 rebounds and 10.4 assists and posted 18 triple-doubles, marks that caught plenty of attention by themselves. But to break the triple-double, rebounding would be a challenge for a 6-foot-3 point guard -- no player that short has ever averaged double-digit rebounds, according to Basketball Reference.

Rebounding, though, is something Westbrook can control. It was just a matter of will, and Westbrook has always had quite a bit of that. He tries to win not just every game but every play. Assists require help; rebounding was largely up to him.

And once the Thunder figured out how to turn his rebounding ability into a weapon, it became something Westbrook's teammates would concede to him. Steven Adams and Enes Kanter would do the blocking out, and Westbrook would soar in for the board. Every Westbrook defensive rebound was its own outlet pass, turning defense into offense in the blink of an eye. The Thunder offense was better after a Westbrook rebound, generating more corner 3-pointers, a higher offensive rating, a better effective shooting percentage and more points per shot.

But Westbrook's rebounding was put under the microscope. Of his 10.7 rebounds per game, 8.6 are defined by the NBA's stats tracking as "uncontested," the highest number in the league. Before you get in a huff, though, Westbrook's uncontested rebound percentage is 80.3; James Harden's is 79.4, LeBron James' is 77.1.

Some scouts had a reasonable explanation for why Westbrook was grabbing so many uncontested boards. Many opposing teams developed a fear of Westbrook in transition, holding their guards back from crashing the glass. That gave Westbrook free rein to chase rebounds, leaving a lot of them "uncontested."

And no doubt there were some unseemly things, such as how Westbrook rebounded almost every missed free throw by opposing teams. His big men would pinch the low block, like defensive tackles taking on blockers so a linebacker could make the tackle. It was subtle stat-boosting, but one that was mostly harmless. The Thunder got the rebound, but the stat happened to go to Westbrook. As Adams and Kanter would sometimes joke, Westbrook owes them a thank you card for it, but they also noted they're happy to do it, because of the respect they have for Westbrook.

The final piece of Westbrook's triple-double puzzle: 6 assists, tallied Friday night against the Suns. Kelley L Cox-USA TODAY Sports

Westbrook has made a habit out of getting the triple-doubles done quickly, too. Of his 41, 13 have been checked off in three quarters or less. He had one before halftime, and eight in under 30 minutes of game time. Westbrook is notoriously organized and meticulous, so it became something like crossing off a chore on a list. Ten rebounds -- check. Ten assists -- check. Once he got that out of the way, then he could go about his business for the game.

And the Thunder have won. They're 32-9 when Westbrook records a triple-double, and 13-25 when he doesn't. (If he'd just get his act together and triple-double all 82 games, the Thunder could've been on a 64-18 pace this season). There's an impact and an influence to Westbrook's statistical dominance, because as much as he has wanted it, it has also been necessary. The Thunder were stripped clean in the summer, and Westbrook was left to shoulder the burden.

In a season in which the narrative was supposed to be predetermined, with all the focus on what the Thunder didn't have, Westbrook eclipsed it all.

He has become the biggest story in the NBA this season. He has met the hype. He has met the moment.

He has done the unthinkable. He has broken through on two of the NBA's most untouchable, unreachable marks. He has batted .400 with a 56-game hitting streak mixed in.

What?

How?

Why?

Because, as most everything with Westbrook can be explained: Why not?