Kyle Shanahan: Christian McCaffrey’s timeline is “unknown”

49ers coach Kyle Shanahan said the timeline for running back Christian McCaffrey's return is unknown."Nobody knows," Shanahan said after the 23-17 loss to the Vikings, via David Bonilla of 49erswebzone.com. "We're dealing with tendinitis, so there's not one person [who] knows. He doesn't know. We don't know. We can take it day by day. By putting him on IR, it's at least four weeks, so that'll give him some time to rest and kind of protect him from himself. Us too. No matter how he's feeling, it's four at the minimum."McCaffrey has spent most of his time rehabbing since Aug. 6, because of a calf strain and Achilles tendinitis. He missed the season opener before the 49ers put him on injured reserve last week.The earliest he can return is Oct. 10 when the 49ers face the Seahawks.Shanahan said McCaffrey has not had a setback in his recovery and, to his knowledge, there have been no discussions about surgery.Jordan Mason has back-to-back 100-yard days in McCaffrey's absence with 28 carries for 147 yards and a touchdown against the Jets and 20 carries for 100 yards and a touchdown against the Vikings.