James, however, has had only a bit role on offense and special teams this season. After returning from a knee injury in Week 4, he has seven carries for 31 yards and one kickoff return for 29 yards. He and guard Joe Looney are the only remaining members of what is quickly becoming an infamous 2012 draft class. Both were healthy but did not play in Sunday's 32-20 win over Arizona. Looney has yet to dress after 25 games.
James, a star running back at Oregon and second-round draft pick, showed frustration with his meager role last month.
"Some things I just don't understand at all," he tweeted. "I don't work at State Farm. I'm not trying to be insurance."
James later deleted the entry, but Harbaugh said he was aware of the running back's feelings.
"He'll be back playing," Harbaugh said. "I know the talk about insurance, et cetera. It's no slight to LaMichael. LaMichael is a very good player. And he's a very valued member of our team."
It's hard to see where James, who excels as an outside runner, fits in an offense that has relied on power running in recent weeks.
Frank Gore finished with 101 yards against the Cardinals and ranks fifth in the NFL in rushing. Kendall Hunter had three carries, including a 6-yard touchdown.
Harbaugh, however, said the 49ers sometimes will dress only three running backs instead of four. The three runners against the Cardinals were Gore, Hunter and Anthony Dixon.
"When all the running backs are healthy and playing, there'll be a week-to-week thing whether we go three or four," Harbaugh said.
James was the team's primary punt returner in the exhibition season. Kyle Williams has taken over the role since the start of the regular season but hasn't added much pop to the return game. The 49ers rank 20th in average punt return yardage, and Williams leads the league with 16 fair catches.
Asked if James could provide a spark as he did in the kick return game last season, Harbaugh said, "He's definitely an option in the return game."