In 2010, LeBron James left Cleveland to build a Miami Heat superteam that would be a powerhouse for years to come. But at the same time, a beast was rising from the west that should've been a great foil. They were the Oklahoma City Thunder.

In a story for ESPN's The Magazine last year, Ramona Shelburne succinctly noted their perceived potential: "It seemed obvious how good the Thunder could be," she wrote. "It was a matter of how many titles, not when they'd win their first."

Bill Simmons stopped short of calling the Thunder a potential dynasty in 2012, but wrote that they seemed destined to win "somewhere between two and four titles."

Instead, they won zero. And now, Kevin Durant, their centerpiece, is gone.

The Thunder's lost dynasty will go down as one of the biggest "what ifs?" in NBA history. Durant, James Harden and Serge Ibaka have all moved on, and Russell Westbrook could be next.

How did the Thunder fail? A series of unfortunate events, some within their control and some outside of it, derailed a run that looked so promising.

The emergence of Loud City

The rise of the Thunder actually began in Seattle when the SuperSonics used the No. 2 pick in the 2007 NBA Draft on Durant. In the two subsequent drafts, the franchise added Westbrook (No. 4 in 2008), Ibaka (No. 24 in 2008) and Harden (No. 3 in 2009), while moving to Oklahoma City in 2008. That gave them an enviable core that they leveraged into a massive, loud fanbase. Their home arena quickly became known as Loud City.

The young squad quickly came together to make the postseason in 2010, losing to the championship-bound Lakers after a hard-fought first-round series. They then made the Western Conference Finals in 2011 and advanced all the way to the NBA Finals in 2012. While the Thunder lost to that Heat superteam in 2012, most believed they'd soon be back. At the time, those 2012 Finals felt like the beginning of a long rivalry.

Instead, the Thunder never even made it back. A quirk in Durant's contract that took effect in that 2011-12 season may have been the start of the downfall.

Durant's weird contract extension

Durant quietly announced his first maximum-contract extension with the Thunder in 2010, and the new deal was about to go into effect for the 2011-12 season. However, the 2011 lockout complicated matters. The new collective bargaining agreement spawned a new provision dubbed the "Derrick Rose Rule" that directly affected Durant's situation.

The Rose Rule allows players signing maximum contract extensions to their rookie deal to earn up to 30 percent of the cap (rather than the standard 25 percent) if they met certain criteria. Durant qualified for this arrangement because he made two All-NBA teams in his first four years. Therefore, the league decided to award him the extra salary even though he signed his deal before the new CBA was put into effect.

The Thunder were not thrilled, but had no choice to go along with it for the time being. Normally, teams can negotiate that extra 30 percent with the player as part of contract negotiations. However, the league elected to simply bestow it on Durant, surprising the Thunder in the process. To rectify the clerical error, the the league bizarrely reimbursed the Thunder in 2013.

But by then, the decision had already made an impact. Not only did it give Durant an extra $15 million over five years, but it pushed the Thunder closer toward the luxury tax. That likely made a significant impact on the next domino that toppled the team's future.

The James Harden trade

Harden was a huge flop in the 2012 Finals, but prior to that, he already proved he had star potential. He was the Sixth Man of the Year in 2012, thriving as a Ginobili-like, uber-efficient dynamo who could run Oklahoma City's offense with and without Durant and Westbrook on the floor with him. But the Thunder faced a cost challenge with the new punitive luxury tax that ultimately led them to make a controversial trade.

Both Harden and Ibaka were up for contract extensions in the summer of 2012. Ibaka signed a four-year, $48 million deal in August, which was fair value, if not team-friendly. Harden, of course, wanted to be paid like the star he'd become, and his maximum contract was four years, $60 million. Due to the aforementioned tax concerns, the Thunder had a dilemma on their hands. Their final offer was a four-year, $54 million deal, and they reportedly gave him only an hour to decide to sign it.

When Harden refused, Thunder general manager Sam Presti pulled the trigger on a massive trade that sent the young guard to the Houston Rockets. In return, the Thunder acquired Kevin Martin (gone after one season), Jeremy Lamb (a bust during his tenure), two future first-round picks and a second-round pick. Those first-round picks became Steven Adams and Mitch McGary. As of right now, the only asset of real value from that trade is Adams, who's one of the more promising young big men in the league.

The trade has been scrutinized until this day, even with Adams' emergence. The Thunder never adequately replaced Harden's wing scoring and playmaking while Durant was still on the team, until it was too late. The acquisition of Victor Oladipo gave Oklahoma City a similar player to Harden, but it came at the cost of Ibaka, one of the other key cogs of the franchise.

We'll never know how long Harden would've stuck around even if he got that maximum offer. Given his status as a rising star, he may have wanted to move on no matter what in order to have his "own" team. But the fact that it was never put on the table in the first place because of those luxury-tax concerns will always haunt Thunder fans. It'll always be a mystery why Oklahoma City never tried to move salary or cut bait with Kendrick Perkins to get the cap relief that potentially could've helped retain Harden.

The untimely injuries

While Harden was gone, the trio of Durant/Westbrook/Ibaka was still formidable, winning a combined 119 games over the next two seasons. But their margin for error got smaller, which was driven home by serious injuries that marred the next three years.

In 2013, Westbrook tore his meniscus in the first round of the playoffs when Patrick Beverley awkwardly bumped into his knee going for a steal. Westbrook then had several complications resulting from that injury that caused him to miss time the following season.

Durant won the MVP in 2013-14 thanks in large part to his prolific play with Westbrook sidelined, and the Thunder looked destined to make a deep playoff run with a healthy team heading into the postseason. Unfortunately, an injury to Ibaka before the Western Conference Finals limited him. Without Ibaka for the first two games and with a hobbled Ibaka thereafter, Oklahoma City lost in six games to the San Antonio Spurs.

The 2014-15 campaign was a disaster. Durant had multiple foot surgeries that limited him to 27 games, while both Westbrook and Ibaka missed good chunks of time. The Thunder missed the playoffs by one game, let go of Brooks and replaced him with Billy Donovan. Presti also made another significant trade, dealing away third guard Reggie Jackson at the deadline in order to acquire big man Enes Kanter.

The 2016 playoff collapse

Durant and Westbrook returned better than ever this past season, although the Thunder didn't inspire much confidence for a title run by consistently blowing leads late in games. With the Golden State Warriors and Spurs putting forth historic regular seasons, Oklahoma City seemed on track to fall short yet again heading into Durant's free agency.

But then the Thunder did the unthinkable and smacked around the Spurs in the second round after looking overmatched in a Game 1 loss. Oklahoma City then won Game 1 at Oracle Arena in the Western Conference Finals and snatched a 3-1 lead by viciously beating the defending champs in Games 3 and 4 at home.

But as we know now, disaster struck. Thanks to torrid shooting from Klay Thompson and the Thunder's crunch-time woes, the Warriors erased that 3-1 deficit to send the Thunder packing.

Blowing that series clearly resonated with Durant and his camp. After hearing a strong pitch from Golden State that centered on forming a dynasty and playing fun, team basketball, the Thunder dynasty that never was officially died when the 2014 MVP decided to join the Warriors.

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So how will we remember this Thunder era? Durant and Westbrook formed one of the most dynamic duos in history, and we should remember their time together fondly, flaws and all.

But it's hard not to view this run as underwhelming. Not only did they only make one Finals appearance without winning a single ring, but the Durant/Westbrook/Harden/Ibaka foursome was taken from us too soon. The financial reasons behind the Harden trade and other moves made the Thunder's failure all the more disappointing.

ESPN recently released a documentary about the lost 90s Magic dynasty. In a few years, we may see a similar one for the Thunder.

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