Penny (knee) won't play in Sunday's game at San Francisco, John Boyle of the Seahawks' official site reports.
The rookie seems to have injured his ankle during Monday's 21-7 win over Minnesota, though he still managed to gain 44 yards on eight carries. Penny's usual allotment of 4-8 carries likely will go to either starter Chris Carson or passing-down back Mike Davis, though J.D. McKissic might also get a few chances. A minor boost to Carson's Week 15 outlook is in order, though he likely will be playing without 340-pound guard D.J. Fluker (hamstring), who is listed as doubtful.