I guess I don't see it quite the same as some here on CMC.. I didn't get to watch the game as I am on the East Coast and rarely get to see SF.
However, I did follow the game on gamecast and CMC broke the first run for 10-11 yards and was averaging 6-7 YPC at the beginning. Then he ran a 1 yard TD which brought his average down and the had -2 carry. Other than that, he ran really well. Circumstances during the game also had an effect as the Niners INT/Pick 6 of a pass early in the 3rd quarter and then Purdy throwing his own INT negated some of CMC's carries in the third quarter and towards the end SF was up 35-17 and there was no need to use CMC in the game. If you take away those 2 carries, he would've had 66 yards on 16 carries for an average of 4.12. A pretty solid average. He couldn't get into the same rhythm in the 3rd quarter as he did in the first half. IMO, he had a very productive game all things considered.
SF black RB picked up his yardage during garbage time, I believe.
BTW, he went over 8,000 career yards to become just the 4th white RB to eclipse 8,000 yards rushing Behind John Riggins, Jim Taylor and Larry Czonka!