We saw Kaepernick do pretty well against the Giants in last week's game to the tune of 23 completions on 35 attempts for 262 yards and two touchdowns. He showed that he is still capable of playing quarterback as long as he isn't rolling out to his left.
Baltimore has been beaten like a drum by opposing quarterbacks, coughing up an all league performance to Josh McCown last week, so Kaepernick is automatically in the conversation by virtue of the Ravens' secondary.
The 49ers' running backs are both nursing their own respective injuries as of today, and it may very well fall on Kaepernick's arm and his legs to win the game against Baltimore. It isn't as though the 49ers defense looks as though it is going to win them the game (25th overall according to PFF).