I pointed out, a few days ago, how weird it was that San Diego Chargers running back Ryan Mathews had only faced the Oakland Raiders twice in his career. I predicted a big game for him. It would appear that I was wrong, and that there's some bad luck associated with the Raiders for Mathews.
In the first half, Mathews carried the ball 3 times for 8 yards. Prior to the game, there was some concern that hamstring tightness might keep him from being able to play.
The Chargers will try to rally back from a 17-0 deficit without Mathews, which means an unbalanced offense that passes a lot more than it runs the ball.
There's no way to predict when Mathews will return to the field for the Chargers. Concussions are a tricky thing. However, other players with concussions this season have missed anywhere from a few days to a couple of weeks. It probably won't be a "long term injury".