SANTA CLARA, Calif. -- As the San Francisco 49ers head down the stretch, Colin Kaepernick is confident of this: His two starting wide receivers are going to do everything they can to get the ball and make plays.The 49ers' passing offense clearly has received a jolt of energy in the past three games since Michael Crabtree has returned from a torn Achilles he suffered in May. Every aspect of the passing game is better. Kaepernick said an enjoyable byproduct is a friendly competition that has developed between Crabtree and wily veteran Anquan Boldin.