49ers select Oregon defensive lineman Arik Armstead 17th

SANTA CLARA, Calif. (AP) — The San Francisco 49ers are stockpiling defensive linemen, and they hardly expect first-round pick Arik Armstead to be polished right away.

Uncertain whether Justin Smith will play again this season, and with Ray McDonald already long gone, the 49ers were searching for another potential pass-rusher with a big body.

Armstead brings that imposing frame at 6-foot-8 and 292 pounds. Now, the Oregon star's task is to become better fast at getting to the quarterback in a division full of talented play-callers.

"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."

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 to an already loaded unit.

Now, keeping players fresh will be more doable.

"Where we're strong, we just got stronger," coach Jim Tomsula said. "It's not the stress of a guy coming in and having to fill a hole."

Armstead is coming home to Northern California. He grew up in Sacramento, and that's where 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 — taking a chance Armstead would still be available, though the Niners had five other players as backup plans.

"You never trade back unless you have an alternative plan in mind. We felt good about two players. Arik was the one we were coveting at that pick," Baalke said. "He's unique in the sense that he's 6-7, he's 290-plus pounds. He's a tremendous athlete for his size and for that position."

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, Armstead 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.

His sack total: 2 1/2.

Yet an ankle injury didn't help his cause. Baalke said Armstead made progress as he got healthy and gained experience.

"I don't think I'm raw," Armstead 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.

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.

Baalke expects Armstead to make strides as he gains strength with more time in the weight room and adjusts to a new level in a "development process," saying, "He's going to have to earn every rep that he gets." Baalke watched Armstead play twice, including once on the bad ankle.

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 — who unveiled black uniforms Thursday that can be worn up to two times this year, the first alternate jersey in team history — 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."