FLOWERY BRANCH — Steven Jackson’s latest hamstring injury is giving Jacquizz Rodgers, Devonta Freeman and Antone Smith a chance to fill the void at running back for the Atlanta Falcons. It’s a tough assignment considering how far the run game has fallen, dropping from 17th in 2011 to 29th in 2012 to worst in the NFL last season. Jackson, the NFL’s active career leading rusher, missed four games with a left hamstring injury and finished his first year as a Falcon with 543 yards rushing and 3.5 per carry — the lowest numbers of his 10-season tenure.