Davis’ main position is tackle, Kelly says

On Thursday, head coach Chip Kelly said then-right guard Anthony Davis was “obviously” one of the team’s best five offensive linemen and joked that he was sleeping better with Davis and tackle Trent Brown forming the right side of the line.

Less than a week later, Davis is back to being a reserve right tackle. Not only didn’t he start at right guard in a 28-0 win over the Rams on Monday night, but Marcus Martin, not Davis, entered when starter Andrew Tiller missed two plays with a foot injury in the first half.

Davis’ abrupt change in roles came two days after he missed practice Saturday because of what Kelly has termed a “miscommunication.” A source has said Davis was absent for a “personal reason,” and the San Jose Mercury News reported he was considering retirement after he left the NFL in 2015 to let his “brain and body” heal.

Did Davis have misgivings about playing guard, a position he hadn’t played since he was a freshman at Rutgers in 2007, before the 49ers asked him to make the move in August?

On Monday, Kelly suggested Davis wasn’t ready to handle his new role in a game that would include a matchup against All-Pro defensive tackle Aaron Donald. Kelly also noted it was his decision — presumably a nod to speculation that Davis requested the move.

“I told A.D. that we were just going to start Tiller going into this game,” Kelly said. “We knew that was a pretty formidable front. We’ll continue to grow A.D. Again, he’s missed a lot of football and he’s coming back. And I’ll give him credit, handling it like a professional. But it was my decision in terms of starting Tiller in this game.”

On Tuesday, Kelly said Davis’ primary position was tackle, but he would need to play guard in an emergency.

“We only have two (backup offensive linemen), so if both guards went down last night, he’s going to have to go in at guard,” Kelly said. First-rounder inactive: Five months after the 49ers traded into the first round to select guard Joshua Garnett, the No. 28 overall pick was inactive Monday.

Kelly said Garnett wasn’t part of the 46-man roster because the 49ers had just two backup offensive linemen and they needed to be versatile. Martin can play both guard and center. Davis can play tackle and guard. Garnett has played only guard.

“Josh is a lot closer,” Kelly said. “I think people see, ‘Well, he was inactive.’ But he’s pushing to be a starter.” Transactions: The 49ers resigned running back DuJuan Harris and released wide receiver Chris Harper, who was promoted from the practice squad Monday.

The 49ers had released Harris to make room for Harper on the roster. Harper is a candidate to return to the practice squad this week. Harris has been released by the 49ers three times since Sept. 3. In a pinch: Kelly said tight end Blake Bell is the team’s emergency quarterback if both Blaine Gabbert and Colin Kaepernick are sidelined during a game.

Bell began his career at Oklahoma as a quarterback before transitioning to tight end. The 49ers’ third-string quarterback, Christian Ponder, was inactive Monday.