49ers writer Tyler Emerick said that RB Reggie Bush was the team's best free agent addition:
If you’ve followed our offseason coverage, you’ve heard Trent Baalke, Jim Tomsula, Tom Rathman, Geep Chryst and Kaepernick all express the same sentiment: Bush, at 30 years old, looks every bit as explosive as ever. The active leader in receptions by a running back with 466 career catches, Bush has urged the 49ers to get him the ball in space. This offseason, that translated not only into the 10th-year pro catching passes out of the backfield, but also getting carries on stretch plays and returning kicks and punts on special teams. Bush sounds like a man with something to prove, and if he can stay healthy, he’ll be a matchup nightmare for opposing defenses.
Bush is expected to fill a third-down role since it looks like Carlos Hyde is ready to carry most of the rushing load, though Jim Tomsula's comments (about Bush being “a runner...not a gadget guy”) indicate that Bush's presence should be a concern for Hyde owners who were initially excited about the young back's opportunity with Frank Gore gone. The 49ers don't typically use their running backs in the passing game, though longtime OC Greg Roman is gone and new OC Geep Chryst may have a different plan in mind.