Clippers rookie Thornwell knows it’s all about confidence

Of all the lessons Sindarius Thornwell learned this season with the Clippers, one stood out for the rookie.

“I learned that confidence is everything,” Thornwell said late Monday night. “To be successful in this league, you got to have confidence. You got to have the mind-set. It’s always a mind-set thing. Being around the vets and watching them work every day and watching them play every game and just them talking to me and working out with them, I learned that if you keep your confidence that it’ll be a lot easier for you.”

At times this season, Thornwell struggled with his confidence, which was to be expected for a first-year player. He had been thrust into the starting lineup and a primary role early in the season when injuries struck the Clippers’ backcourt.

He was riding high for a while, playing in 14 games in November and 14 in January.

But his play began to decline and his playing time dropped to three games in February.

Thornwell stuck with it during the down times and eventually his confidence returned.

“He started out great,” coach Doc Rivers said. “He understood who he was. He’s a defensive player. And he then kind of got lost a little bit, typical rookie year. But what I’m impressed with is that he gathered himself. He caught himself.

“One thing I love about him is [even though] he makes mistakes, he’s young, but he plays hard. He covers up for some of them with his hard play. He’s a tough kid. When you project out, you look at him as a very, very, very good NBA defender.”

The 6-5, 215-pound Thornwell knows Rivers is right, but then he went out and scored a career-best 20 points against the New Orleans Pelicans on Monday night, showing his offensive skills.

Thornwell probably will get more playing time in the Clippers’ season finale against the Lakers on Wednesday night at Staples Center.

“Since we’re not making the playoffs, I think this is a opportunity for us young guys to just come in and show what we can do and gain some confidence,” Thornwell said. “Use these games to get better and continue to grow.”

Thornwell played in 72 games this season, starting 15, and averaged 3.8 points in 15.6 minutes.

Besides giving him tough defensive assignments, the Clippers allowed Thornwell to handle some point guard duties late in the season.

That just showed how much his game has evolved as the season progressed.

“It’s all just growing, just staying with it and staying consistent with it,” Thornwell said. “Whether I was playing or not, I was coming in working every day on what I needed to get better at and keeping my confidence. I think that’s the biggest thing is just getting the opportunity and having the confidence to take advantage of the opportunity. I just stayed grinding and waited for my opportunity.”

Etc.

Guards Lou Williams (sprained right ankle) and Austin Rivers (right elbow soreness) didn’t play against New Orleans on Monday night, and both are listed as questionable for the game against the Lakers.

CLIPPERS UP NEXT

VS. LAKERS

When: Wednesday, 7:30 p.m.

On the air: TV: Prime Ticket; Radio: 1150, 1330.

Update: The Clippers have defeated the Lakers all three games this season by an average of 12 points. They have defeated the Lakers in 17 of their last 18 meetings, including the last six straight.

broderick.turner@latimes.com

Twitter: @BA_Turner