Russell Westbrook reacts after hitting a basket against the Los Angeles Lakers. (Sue Ogrocki/Associated Press)

Russell Westbrook picked off the pass, picked up momentum, plowed through the arm tackle of Ramon Sessions and tossed in an underhand layup — from about 18 feet away. Then Westbrook angrily nodded, screamed and stomped up and down. He refused to slow down, couldn’t be held back and admittedly got lucky.

The turning point of the Oklahoma City Thunder’s series-clinching Game 5 victory over the once-removed champion Los Angeles Lakers on Monday exemplified Westbrook’s career: Place a barrier in front of him and watch him knock it down.

Westbrook was arguably the most scrutinized player not named LeBron James last postseason. His spastic temperament was considered a liability to the Thunder’s championship hopes, and his every shot was second-guessed and viewed as a rebellious refusal to defer to media darling Kevin Durant.

The criticism made Westbrook a little more guarded and withdrawn, but losing to eventual champion Dallas in the Western Conference Finals is what made him determined to make amends.

“It’s definitely helped me,” Westbrook said of his detractors. “Last year, we got put out in the conference finals. I was definitely disappointed in that. Coming into this year, I wanted to come in and help my team and become a better leader.”

This postseason, Westbrook has struck a decent balance between erupting for much-needed scoring bursts and getting out of the way when either Durant or sixth man of the year James Harden have it going offensively. He has also reined in his tendency to be wild with the basketball by committing just four turnovers against the Lakers.

The most biting criticism Westbrook has heard this time around has been for his unique sense of style, with him donning several colorful outfits in postgame interviews — including a fishing-bait shirt and accompanying oversized red glasses that didn’t have lenses because, “I see better without ‘em.”

Westbrook appears to be in on joke. As he got ready to take his seat at the podium after a win last Saturday — in a shirt that appeared to be inspired by a bag of Skittles — Westbrook asked reporters, “Why is everybody laughing?”

After becoming the second team in NBA history to defeat the past two champions in the playoffs, the Thunder is back in the conference finals, against the San Antonio Spurs — a team with collective experience and consistent blandness that you won’t find in the 23-year-old Westbrook.

How many times have you seen a member of the Spurs hit a three-pointer, blow the tips of his index fingers as if they were guns, then stick them into imaginary holsters — with his team down by 10 points? That’s Westbrook.

And the Thunder wouldn’t have it any other way. “He’s taken our franchise to a level that we can say, we can compete with the best,” Thunder Coach Scott Brooks said. “He’s about winning basketball games. Is he a complete player? No. And he knows that. He’s going to continue to work to get to another level.”

Westbrook wasn’t created by the NBA hype machine, didn’t arrive with a sneaker company trumpeting his every step. He hasn’t earned his stardom as much as he snatched it and strapped it over his shoulders. “He has a battery pack on his back,” Harden said.

This is a player who got a scholarship offer to UCLA only after Jordan Farmar declared for the NBA, then helped the Bruins reach back-to-back Final Fours without much fanfare. The Thunder took him fourth and was roundly criticized for taking him too high.

He was added to the Team USA Select Team in 2008 after Jerryd Bayless got injured — and only because he happened to be in Las Vegas training on his own at the time — and two years later was an overpowering force on a team that won FIBA world championship.

Westbrook has had to hear that he is not a real point guard for much of his career, but he already has two all-star appearances, all-NBA second-team honors, and has piloted three consecutive 50-win seasons and back-to-back Northwest Division titles in just four years.

“I’m not going to sit here and tell you we thought he would be this type of player in his fourth season as a NBA player,” Thunder General Manager Sam Presti said. “Russell had some qualities as a competitor and as a person that we thought would be important for building a foundation of a team that could sustain success.”

The Thunder has stayed committed to Westbrook. It didn’t entertain dealing him last offseason and signed him to a five-year extension worth around $80 million in January, even as many wondered if he was the best talent to pair with two-time MVP runner-up Durant. The two players have clashed at times but are friends, and Durant knows that no matter how many scoring titles he wins, the Thunder wouldn’t be where it is without the feisty and fiery Westbrook.

“We don’t really care about the outside,” Durant said. “We’ve had belief in him from Day 1. What attracted me to Russell so quickly, is that we have the same personality. Our work ethic is the same. Our passion is the same. And our overall care for the game. We always respect the game. We want to beat each other to the gym each day, the last to leave and we just always want to challenge each other — in a good way.”

Westbrook credited Durant for helping him stay positive during different stages of this season but he doesn’t believe that their work is done.

“We’re back to where we were last year,” he said after the Thunder closed out the Lakers, “and now we got to make the next jump.”

Staff Writer Jason Reid contributed to this report.