Simms (undisclosed) missed Atlanta's last two preseason games with an injury, Kelsey Conway of the Falcons' official site reports.
The 30-year-old Simms rejoined the Falcons after Kurt Benkert suffered a toe injury in the Hall of Fame Game and made exhibition appearances against the Dolphins and Jets before being saddled with an injury of his own. The nature and severity of the issue has yet to be revealed, but Simms's absence does not bode well for what began as a puncher's chance at a 53-man roster spot. If he's able to return soon, he is a candidate for a practice squad spot, though Danny Etling -- who's demonstrated impressive rushing ability and competent passing -- may offer higher upside for such a role.