The 49ers needed a linebacker. The Vikings had depth at the position and trust that rookie Eric Kendricks can step up as a starter. So Vikings General Manager Rick Spielman pulled the trigger today on a trade that sends starting middle linebacker Gerald Hodges to San Francisco for a sixth-round draft pick next year and rookie center Nick Easton.

The sixth-rounder replaces the sixth-round pick the team traded to San Diego for backup offensive lineman Jeremiah Sirles. And the opening at middle linebacker clears the way for Kendricks to step forward as the nickel linebacker to a three-down starter. Audie Cole, another player Spielman voiced confidence in, moves up to the backup role.

"I know [Kendricks] is a very instinctive football player," Spielman said. "Each week, you see the more reps he's getting the more comfortable he's getting with the speed of this game. And he makes plays when he's out there. We drafted him because of how strong we felt about him coming out. When we evaluated him in college, you're starting to see all that come as he adjusts to the speed of the NFL. He's a very instinctive linebacker who makes a lot of plays."

So the trade made a lot of sense to Spielman.

"This was an opportunity where a team had a need and we had added depth at that position," Spielman said. "It was something we went ahead and pulled the trigger on."

A fourth round pick in 2013 out of Penn State, Hodges moved to middle linebacker for the start of the season – saying it was the first time in his life he played the position. He played in 25 games over his first two seasons for the Vikings, starting seven at outside linebacker.

Easton, 6-3 and 300 pounds, was an undrafted free agent out of Harvard who signed with the Ravens following this year's NFL draft. He was traded to the 49ers before the season started for a conditional draft pick on Sept. 5.

Vikings starting center John Sullivan will miss at least half the season after back surgery, and the Vikings offensive line struggled in Sunday's loss at Denver.