After Oklahoma City reached the 2012 NBA Finals, James Harden set expectations.

“A dynasty is being built here,” Harden said.

It sure appeared to be trending that way.

The 2010 Thunder were the youngest playoff team in NBA history. In fact, they were so young, they kept the same core, and the 2011 Thunder became the second-youngest playoff team in NBA history. The 2012 Thunder were the youngest NBA Finals team in decades.

Oklahoma City was loaded with talent. Kevin Durant, Russell Westbrook and Harden were future MVPs. Serge Ibaka became a near star.

The Thunder were a nova.

But like all stars, their enormous and powerful fire eventually burned out.

Oklahoma City closed a chapter by agreeing yesterday to trade Russell Westbrook to the Rockets for Chris Paul. The Thunder have now completely turned over their roster since the 2012 Finals, leaving Harden’s proclamation unfulfilled.

Harden was the first to go. When he didn’t agree to a contract extension, Oklahoma City traded him to Houston in 2012. Durant left for the Warriors in 2016. Ibaka got traded to the Magic the same summer. Now, Westbrook exits.

After ascending so far so quickly, the Thunder not winning a title with any of those players is a historic disappointment.

Oklahoma City’s average age (weighted by postseason playing time) was 22.9 in 2011 and 23.8 in 2011. It was still just 25.7 in 2012, when the Thunder lost to the Heat in the NBA Finals.

Just four teams since the NBA-ABA merger have reached the Finals while so young. The other three eventually won a title.