Last week, the fantasy football world was stunned when the 49ers de-activated RB Frank Gore for the team's eventual four-point loss to the Atlanta Falcons. When fill-in RB Maurice Hicks ran in a 9-yard score on the 49ers first drive, he cemented the idea that he would be the goal-line back in Gore's absence. Without another goalline opportunity, this idea could not be dispelled.
However, one must note that fellow fill-in Michael Robinson carried the ball 17 times for 67 yards and caught two passes compared to Hicks' 9 carries for 47 yards and a TD and one reception. That is nearly a 2:1 advantages in touches for Robinson. This leads me to cautiously conclude that there isn't enough evidence to state Hicks will be the goalline back.
Given Robinson's relative inexperience, I checked Pro Football Prospectus to see what it says. PFP contains an article "Top 25 Prospects" by Michael David Smith. At the top is Falcons' RB Jerious Norwood and Chargers' RB Michael Turner. More surprising was the player that came in at #22 - San Francisco 49er Michael Robinson.