Ruf was placed on the 10-day injured list with a neck strain Friday, retroactive to Sept. 27.
Ruf has had limited playing time over the last few weeks, but he's apparently been dealing with a neck injury that has kept him off the field recently. Although the move was backdated, the 36-year-old will be forced to miss the rest of the regular season. It's not yet clear whether he'll be healthy in time for the postseason.