FLOWERY BRANCH — With former Pro Bowl cornerback Brent Grimes out for the season, the Atlanta Falcons are counting on four career backups to fill the void. Losing Grimes to a torn Achilles tendon means the Falcons must face Peyton Manning and the Denver Broncos on Monday night without their best cornerback. Christopher Owens and Dominique Franks have struggled in the past for Atlanta, but the team is counting on both players to take plenty of snaps.