49ers Draft Sacramento's Arik Armstead

SANTA CLARA, Calif. (AP) — Uncertain whether Justin Smith will play another season, and with Ray McDonald already long gone, the San Francisco 49ers were searching for a pass-rusher with a big body.

Oregon defensive end Arik Armstead brings that with a 6-foot-8, 292-pound frame. Now, his task is to become better fast at getting to the quarterback in a division full of talented play-callers.

San Francisco selected Armstead with the No. 17 pick in the NFL draft Thursday night, boosting another position where the 49ers looked to add depth this offseason.

"We're going to push it to the next level," Armstead said. "I'm going in there open-minded, looking to work hard and be coached. I think I'm definitely a nickel pass-rusher."

Armstead will come home to Northern California. He grew up in Sacramento, and that's where 49ers coach Jim Tomsula reached him with the call that he would be joining the Niners.

"It's going to be huge for me," Armstead said. "I want to represent this part of the state the right way."

San Francisco general manager Trent Baalke traded the 15th selection to San Diego to move down two spots Thursday. As he likes to do, Baalke added a big body with a quick first burst off the line.

Before the draft, Baalke said: "I like big everything. Yeah, we like big kickers, too."

A 13-game starter for the Ducks last season as a junior, he had 46 tackles, and had a career-best nine tackles and recovered a fumble in Oregon's loss to Ohio State in the national championship game.

"I don't think I'm raw," he said. "If people watch film on me I'm a technically sound player. ... My role was to be disruptive. I played my position well."

While the Niners have no plans to rush Smith into a decision, the 14th-year defensive end is considered a short-timer even if he plays in 2015. Baalke said Smith's unsettled situation would not affect how the Niners might look to draft.

"I have no idea what's going on with that. That's a decision he's going to have to make," Armstead said of Smith's status.

49ers CEO Jed York provided some glimpses from the draft room via Twitter, offering, "Will #TraderTrent move up?!?!" and "Phones are ringing EVERYWHERE."

Following the retirements of five-time All Pro linebacker Patrick Willis and Chris Borland shortly thereafter following his standout rookie season, changes on defense are expected under defensive-line-turned head coach Tomsula and defensive coordinator Eric Mangini.

Armstead played twice at Levi's Stadium in the venue's inaugural season last year, including in the Pac-12 title game.

"That stadium has treated me well," he said. "I'm looking forward to playing my next game there and playing as long as my career is in there."

The 49ers also received a fourth-round pick this year and a fifth-round selection for 2016 from the Chargers in the swap. With the addition of the 117th choice, San Francisco will have three fourth-round selections in all — choosing again at 126 and 132.

While he didn't grow up only rooting for the 49ers, Armstead immediately felt comfortable around the team during his pre-draft, get-to-know-you session.

"I had a good visit when I went there," he said. "I felt comfortable with everybody. I really loved it there."