One of the most common mantras for NFL free agency is that you cannot build a team through free agency, it must be the draft. The logic is somewhat sound. If you draft well, you can have great players at discount prices. While in free agency, you’re competing to be the highest bidder for players that were let go by their former teams. You tend to overpay, and the talent level may not be as good as young, high-potential rookies.
But there are plenty of counterexamples to this strategy. Just last year, the Jacksonville Jaguars went on a shopping spree in free agency and it helped the team jump from a pathetic 3-13 to a legitimate AFC Championship contender in just one year.