PHOTOS: Meet the NFL Draft 2015 round 1 picks
San Francisco general manager Trent Baalke traded the 15th selection to San Diego to move down two spots Thursday. With Ray McDonald gone and Justin Smith uncertain to return, Baalke added a big body - 6-foot-7, 292 pounds - with a quick first burst off the line.
Armstead will come home to Northern California. He grew up in Sacramento.
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.
49ers CEO Jed York provided some glimpses from the draft room via Twitter, offering, "Will #TraderTrent move up?!?!" and "Phones are ringing EVERYWHERE."