A day after his team’s not-fit-for-primetime performance against the Steelers, Panthers head coach Ron Rivera closed his Monday afternoon press conference by saying, “And remember, we are moving on now.”Minutes after that, Rivera shared injury news that revealed the Panthers will have to move on without two of their top three running backs and their second-best linebacker this week.Running back Jonathan Stewart “severely” sprained his right knee when his foot got caught in the ground while being tackled by former Carolina safety Mike Mitchell in the third quarter. When he limped to the sideline, the oft-injured Stewart slammed his helmet in frustration. He will undergo an MRI on Monday, and if he practices ahead of the Ravens game, it won’t be until Friday at the earliest.Fullback Mike Tolbert has already been ruled out for next Sunday. He has a hairline fracture in his knee, and he is week-to-week.Rivera wouldn’t clarify the injury that knocked linebacker Thomas Davis out of the second half Sunday night, but “it has nothing to do” with his right knee that’s been surgically-repaired three times. Like Stewart, Davis will be re-evaluated Friday, but it appears he’s unlikely to play against the Ravens.While they’re not at Davis’s level, the Panthers have capable backups in A.J. Klein, Chase Blackburn and Jason Williams. The running back situation is much worse.DeAngelo Williams (hamstring) and Fozzy Whittaker (quad) were both held out against the Steelers. Rivera is hopeful Williams will return this week, but that was the case last week as well. Whittaker is more likely to come back later rather than sooner.The Panthers’ 10 rushing attempts Sunday night was the fewest in their 20-year history, and their 42 rushing yards was their lowest since they gained 10 just yards in the 2012 season opener at Tampa Bay.Carolina’s ground game is now ranked 29th in the league, and that number is unlikely to rise much via runs by Cam Newton. The banged-up quarterback is averaging three carries in 2014 after averaging more than seven carries per game over his first three seasons.Rivera admitted Newton is “not quite where we need him” to run the ball effectively. And when asked if the run game can be a threat if Newton’s not, Rivera replied, “It’s going to have to. That’s the bottom line.”