Mike Singletary wanted to build a defensive-minded squad with a power running game centered around halfback Frank Gore.
Unfortunately, Gore may have been overused in 2010, as he went down with a hip injury in San Francisco's Week 12 Monday night matchup against Arizona. He missed the last five games of the season.
Gore's role, as well as that of any other 49ers tailback, will be much more dynamic under Harbaugh. Running backs in the west coast offense perform a larger variety of tasks, including a heavy dose of pass blocking and route running.
As exemplified by old 49ers back Roger Craig, a running back should be capable of running swing routes and catching screen passes as well as powering up the gut.
To ease pressure on the runner, the team will mix in more off-tackle runs and sweeps so that the back isn't pounding the A and B gaps all day.
Frank Gore is an All-Pro tailback with good hands out of the backfield and should do fine in the new system.
But Mike Singletary did not leave his successor much to work with. Between his alleged role in spurring Glen Coffee's premature retirement and the drafting of bruiser Anthony Dixon, Singletary failed to leave a change-of-pace back that would fit in perfectly in Harbaugh's system.
Harbaugh's inability to mold his backfield from the free agent pool could hurt the productivity of 49er backs in 2011.
Lockout Damage: Medium-High