Last year, Steven Jackson received a vast majority of the carries for the Rams (over 86% of the carries by RBs) but he only averaged 3.8 ypc. Darby and Toston combined for a pedestrian 53 carries for 161 yards (3.0 ypc).
Let's look at ways the Rams are attempting to help improve those numbers, while giving Steven Jackson less carries.
SIGNING HARVEY DAHL: The Rams signing a big nasty to help Jason Smith clear the way on the right side is probably going to be the biggest thing they did to help the run game. His intensity should also help Jason Brown's game (hopefully).
SIGNING CADILLAC AND NORWOOD: Bringing in a couple solid veterans to take some carries from Jackson can be vital to him being fresh at the end of the season (hopefully, for a playoff push). I know there are a lot of concerns on the injury issues with both backups, but I'll trust the Rams' judgement and hope they can stay fresh, considering Jackson demands the majority of the carries, regardless.
JOSH MCDANIELS' OFFENSE: Josh's offense can open up the lanes by keeping the safeties and linebackers busy in coverage and force them out of the box. He also spends a lot of time in the shotgun formation, which Jackson had a better ypc average out of last year. This revamped offense brings me to my next point.
SAM BRADFORD: It's Sam Bradford's sophomore year and I, for one, don't think he'll be having any kind of slump. Be it from the 'sophomore slump' or learning a new offense. Sam's one year wiser and the coaches will be more willing to put the game in his hands.
With all of those things, if Jackson could bring his average up to just 4.5 ypc, He could do the same this year as last year (1,241 yards rushing) with just 276 carries (54 less carries than last year). Having said that, if Cadillac and Norwood can average over Darby's and Toston's 3.0 ypc while taking those carries from Jackson, then the RBs have done their job to help the offense and help Jackson prolong his career.