Around this time every year, fans get bent out of shape hoping their favorite teams sign free agents. Some teams, like the Colts, stay away entirely. The reason is because free agency rarely produces solid players.
Why doesn't free agency pay off? Simple: restricted free agency and the franchise/transition tags. Essentially, if the team that drafted a player still wants that player, it's easy to keep him. The restricted tenders and the tags mean that a team rarely has to lose a player until it wants to. The quintessential example of this for the Colts was Edgerrin James. James became a free agent after the 2004 season. The Colts franchised him for a year, before cutting him lose. He signed a big deal with Arizona, but he was mostly used up and worn out by that time. He struggled behind a bad line, and never paid off the Cardinals for their multi-million dollar investment. If a player is a free agent in the NFL, it means his original team simply no longer thought he was worth the money. Add to that teams bidding against each other, and the result is rarely a payoff.
Some fans know this intellectually, but they don't realize just how grim the prospects of signing a good free agent really are. If you go back over the list of the top free agents for the past four seasons, it's telling. I've gone through every free top free agent who actually changed teams in that span, and the results should scare you off from free agency forever.