It's easy to get caught up in the free-agent frenzy and have your hopes rise and fall with every cut and signing. I know I'm guilty of it. One man's trash is another man's treasure as they say. We did pretty well with Whitworth and Woods last year also Webster and Robney-Colemen were free agents (i think). Over the years though I think the results league-wide would bear out that most big free agent signings don't match up in terms of cost vs production. Some of the biggest players in free agency are often some of the worst clubs, certainly the Rams were often terrible at it. Why are these guys not getting re-signed by their teams? Age? Declining production? Money concerns? Sometimes it's less sinister and just scheme fit with a coaching change.
If you're trying to match the success model of a team like the Patriots - its' about Quarterback, Coach, and Culture. Free agents come and go and they just keep chugging away while teams like the Dolphins pay ridiculous money to a DT -who has had good numbers for them, but never elevated their overall defense and never made the difference in winning and losing.