If anything, it’s their right guard, Mike Person.
Not to say Person is bad. He’s a decent right guard. The 49ers almost won a Super Bowl with him, so he can’t be terrible. He certainly could start for other teams. But the 49ers can do better than Person. They can cut him and sign a free agent this offseason.
Person started the past two seasons at right guard for the 49ers and, when he was on the field, the offense generally performed well. When he wasn’t on the field, the offense generally performed well, too. Person isn’t an impact player.