49ers RB Brandon Jacobs ''isn't concerned'' with competing for carries with Frank Gore. ''That part will work itself out,'' Jacobs said. "My role is going to come off how much I earn. I'm going to earn everything I get." The 49ers may enter the year planning to limit Gore's role, but have yet to commit to Jacobs as their short-yardage back. If he falls behind Kendall Hunter on the depth chart, he won't be guaranteed a spot on the Opening Day roster.