Posted by ESPN.com's Mike Sando
The 49ers have lost one player from their practice squad -- running back Kory Sheets, signed by the Dolphins -- while adding a familiar one.
Offensive lineman Khalif Mitchell, who went to camp with the 49ers, re-signed to San Francisco's practice squad.
Sheets enjoyed a strong exhibition season, but the 49ers did not sign him to their active roster after losing starter Frank Gore to injury. With Gore returning after the bye, the 49ers should be fine at running back, even if they had hoped to keep Sheets on their practice squad.
Contracts are not permanent in the NFL, of course. We've seen promising young running backs leave NFC West practice squads for 53-man roster spots elsewhere, only to return. It happened to the Seahawks with Justin Forsett last season.