Free Agency is how losers build football teams. No team has won, let alone competed for a Super Bowl by building their team and plugging multiple holes through big money deals in free agency. Over the years we've seen some real egregious examples from Washington, Jacksonville, New Orleans and LAC have nothing to show for it. And the biggest mistake in free agency, in my opinion, is dishing out big money deals to offensive linemen. The O-Line is probably one of the only positions in the NFL where you can bring a career average player to good with coaching given the nature of the position.
If you don't have a foundation built from the draft and a pipeline of signing and retaining those draft picks to second and third deals you have no shot, and signing guards to 90 million dollar deals when you can get a guy in the third round to perform the same, if not better, solely on scheme makes it a franchise killing mistake.