SANTA CLARA -- Three potential starters who missed the 49ers' most recent game were on the field Tuesday as the team came out of its "mini bye" weekend.
Tight end Vance McDonald (hip) missed the last two contests while defensive linemen Glenn Dorsey (knee) and DeForest Buckner (foot) were unable to play in Thursday's loss to the Cardinals.
The 49ers allowed 157 rushing yards to Arizona running back David Johnson in that game, a common theme this year for a 49ers defense that ranks 31st in average rushing yards allowed.
Defensive coordinator Jim O'Neil said Tuesday that was his greatest concern and that he and his staff spent the last few days figuring out what the defenses has done well and where it has struggling and honing the approach accordingly.