If you are not familiar with what a "franchise tag" entails, it simply means that teams can elect to construct an exclusive or non-exclusive deal with any one player on the teams roster.
An exclusive deal is set by a league-wide standard relative to the top five players at their position or a 20 percent increase from the players salary for the previous season. The tag is set at the higher of the two scenarios. They are for one year and that player is not allowed to negotiate with any other team.
On the other hand, a non-exclusive deal will take the lesser of the two aforementioned scenarios but will allow that player to negotiate with another team. The team will have the option to match any other teams offer should the player receive one.
Seeing as the Falcons just freed up roughly $16 million dollars in cap space by releasing three key starters, it would have been counter productive to clutter that much needed cap with any exclusive deals.
The only truly plausible deal would have been with William Moore, who would have met the worth of $6.8 million dollar deal he would have received with an exclusive tag. Although it was recently reported by D. Orlando of the Atlanta Journal Constitution that he expects the Falcons to sign Moore to an estimated five-year, $25 million dollar deal.
Grimes would have demanded around nearly $10 million dollars regardless of the tag, where as Sam Baker would have been set to make roughly $3 million with a non-exclusive deal and $10 million exclusively.
As of now, it's just a waiting game for Atlanta fans until the floodgates of free agency open March 12, 2013.