Gerald Hodges — a versatile 24-year-old athlete who once backed up both outside linebacker spots, started at middle linebacker this season and was considered veteran Chad Greenway’s heir apparent as early as next season — was traded by the Vikings to the San Francisco 49ers for a sixth-round draft pick in 2016 and rookie center Nick Easton on Tuesday.

That’s how much confidence Vikings General Manager Rick Spielman has in his depth and a belief that rookie second-round draft pick Eric Kendricks is ready to be promoted from nickel linebacker to the team’s first three-down playmaking middle linebacker since E.J. Henderson was in his prime.

“Each week, as you see the more reps he’s getting, the more comfortable he’s getting with the speed of this game,” Spielman said. “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.”

It wasn’t an easy decision. Hodges had come a long way since being drafted by the Vikings in the fourth round in 2013. He played special teams as a rookie and made seven starts — three on the weak side and four on the strong side — last year. His interception return for a touchdown 12 seconds into the victory over the Jets set the franchise record for fastest defensive score.

When the Vikings were uncertain this summer that Kendricks could handle being a three-down player immediately, Hodges was moved to middle linebacker in the base defense despite having never played the position in his life. He was tied for third on the team with 20 tackles while starting the first three games this season. Kendricks started Sunday in Denver because the Vikings opened the game in their nickel package.

“I think Gerald has played very well for us,” Spielman said. “He’s grown up tremendously. Sometimes, these are difficult decisions, but when you have depth and youth at a position, and you can make a move from a business perspective on getting your team better when you have extra pieces to move, I think you always have to look at those.”

In Hodges, the 49ers get a player who likely will challenge Michael Wilhoite as the starting inside linebacker next to NaVorro Bowman in a 3-4 defense that has been decimated by the release of troubled outside linebacker Aldon Smith and the retirements of inside linebackers Patrick Willis and Chris Borland.

Hodges had eight tackles in the season opener at San Francisco, but the Vikings also gave up 230 yards rushing in a 20-3 loss. Since that game, the 49ers have lost three consecutive while falling to 29th in scoring defense (29.3 points allowed per game).

Spielman wouldn’t say which team made the first call.

“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.”

Kendricks has 19 tackles, has shown speed in coverage and notched his first career sack, against Peyton Manning, on Sunday. Spielman also voiced comfort with Audie Cole, who is expected to be Kendricks’ backup, as well as rookie seventh-round draft pick Edmond Robinson and Brandon Watts, a second-year player who’s now on the practice squad.

As for next year, if Greenway isn’t brought back for an 11th season, Kendricks would be an option outside or in the middle, depending on how the roster is shaped.

The sixth-round draft pick Spielman acquired replaces the sixth-rounder he used to get backup offensive lineman Jeremiah Sirles from San Diego on final cutdown day. As for Easton, he’s a long-term developmental player the Vikings tried to sign as a free agent out of Harvard. Easton signed with Baltimore and was traded to San Francisco on final cutdown day. He played special teams only the past two weeks.

Easton’s inclusion in the trade had nothing to do with John Sullivan’s health status, Spielman said. Sullivan, who had back surgery, is on injured reserve with the designation to return this season.

Assessing the season

Spielman revealed the trade during his annual bye-week session with local reporters. Here are three more highlights from that session:

• On whether he would consider bringing in kickers to compete with struggling Blair Walsh: “Blair is going through a little bit of a slump here now, but I think there’s no question that he’s our kicker. … [Punter] Jeff Locke had some struggles last year and this year he’s punting lights out. Part of having young players is sometimes you’re going to have to get them through that adversity.”

• On receiver Cordarrelle Patterson’s slow progress: “He’s made so many strides since a year ago and he continues to make strides. … With Cordarrelle, you can’t ask for a kid that’s working as hard as he can. … These coaches are trying to put personnel together with specific packages.”

• On what he thinks is the next step for quarterback Teddy Bridgewater: “Just continuing on the direction he’s going. He’s just going to get more and more comfortable as we go forward. The thing he’s really doing a good job on is, I think, two third-and-10 situations in this last game, he made plays with his legs to keep drives alive. He’s been very good with his decisions. … He’s only going to get better with the more experience and the more games he’s going to get.”