PORTLAND -- Forget about their youth, their inexperience, and the difficulty of the Western Conference. Forget all that, and just know this: The Thunder are going to the playoffs. Their 89-77 win over the Blazers on Tuesday showed a good example why, as Oklahoma City demonstrated how its defense and newfound depth could carry it on a night when the starters couldn't deliver.

The Thunder wrested a tough road win from Portland by going on a 15-2 run in the first six minutes of the fourth quarter with just one starter on the floor. Instead of the Kevin Durant and Russell Westbrook show, it was the likes of Serge Ibaka, James Harden and Eric Maynor who turned this one around for the Okies.

More on them in a minute. In the meantime, take note of today's standings. The Thunder are 30-21, good for sixth in the conference and a full three games ahead of No. 9 Houston in the Western playoff race. They're closer to third than they are to ninth, and looking ahead they have one of the league's most favorable schedules. Barring injury, they're going to make it, and they might even be hosting a first-round playoff series.

The reason they'll make it is the same reason they won their sixth straight game Tuesday: They've become much more than just the Durant show. Yes, there were the usual doses of Durant, who finished with 33 points and 11 rebounds and shook up Andre Miller so badly on a first-quarter crossover move that it left the Rose Garden crowed gasping.

"I just thought I ran past him and thought he was behind me a little bit so I had an advantage," said Durant. "I didn't really hear the crowd, I was just trying to make a play."

Durant also finished off the night with a pair of jumpers off crossovers over Nic Batum -- one of the few opponents Batum has faced that can shoot over him with such ease. However, Durant had an uneven night by his lofty standards, with only one assist and several defensive lapses that harkened back to his first two seasons. Point guard Westbrook was off his game too, finishing 2-of-9 with four turnovers.

Instead, it was a suffocating defensive effort from a young team that surprisingly ranks fifth in the league in defensive efficiency that got the Thunder out with a win. Although the Blazers are admittedly an easier foe minus Brandon Roy, the Thunder also forced Portland completely out of its game offensively.

Oklahoma City frustrated Portland all night by fronting LaMarcus Aldridge in the post, with many of Portland's 24 turnovers coming on botched entry passes that were stolen by rotating weakside defenders. Aldridge made life easier for the Thunder by inexplicably passing out of one-on-one matchups on the block, but some of that may have been because of how hard he had to work to get the rock in the first place. He was held to 15 points and committed four turnovers.

"The main reason why we won was Jeff Green did a great job denying the ball to Aldridge," said Thunder coach Scott Brooks. "That's been our strategy, to take the ball out of the post, don't let the guy have an easy catch, and if he does make him go out to 15 feet and then we can shrink the floor."

Despite that effort, Oklahoma City trailed 61-59 entering the fourth quarter until the second unit came in to spark a game-changing rally. Ibaka, a rising defensive force who blocked four shots, swallowed Aldridge whole in the fourth -- he held Portland's top weapon without a single shot attempt.

"That was about as good as we can possibly play [defense]," said Brooks. "Jeff did a great job and then Serge came in the fourth quarter and was just as good."

Joining Ibaka and Green on the court in that fourth-quarter run were Nick Collison, Maynor and Harden. So the Thunder were playing three rookies and sitting two of their three meal tickets, yet they held the Blazers to a mere two points in the first six minutes of the fourth.

Yes, Roy's absence helped. "Let's face it, Roy's out, it's a completely different team," admitted Brooks. "We got them on a good night."

But it was symbolic of the Thunder's progress that they were so confident they could shut down a Portland team that still had significant offensive weapons on the floor even in Roy's absence.

"As long as we got back and didn't give up offensive rebounds," said Collison, "We felt like they couldn't score against our half-court defense.

The shockingly rapid progress of Oklahoma City's young players is the primary cause of their sudden defensive prowess, but Collison showed that old dogs can learn new tricks too. He made a huge play at the five-minute mark with the Blazers down eight and trying to ride their home crowd back into the game. Andre Miller caught the ball in the wing on transition and sliced toward the basket when Collison unveiled his newfound specialty, taking a charge, to thwart his drive.

"I just ran back and saw he was going to go to the hoop," said Collison, who sprinted back to pick up Aldridge and then quickly pivoted into position when Miller angled from the right wing toward the basket. "I knew it was going to be a close play because I was running, [and] he was running. It was one of those plays where you're probably going to either foul him because he's coming into you, or you try to take a charge, and I got set in time. Or at least I made it look that way."

Harden, meanwhile, had two key deflections and scored all 13 points in the run, supplying all but two of the Thunder points in that stretch.

Add it all up, and it's another milepost for the Thunder in their rapid ascension from doormat to dominance. They already have more wins at the All-Star break than they did all of last season, and if they just win half their remaining games they'll double last year's win total.

"It's something we didn't think about early in the season," said Durant. "We just wanted to take it one day at a time and get better, and I think we've done that."

So much better, in fact, that they're well on their way to a playoff berth that, a few months ago, seemed unlikely in such a packed Western Conference field.

John Hollinger covers the NBA for ESPN Insider.

ESPN.com writers and TrueHoop Network bloggers chatted with fans and gave their in-game opinions throughout Tuesday's games -- all in Daily Dime Live.