There is an old saying about the strength of the wolf is the pack, and I think there is a lot of truth to that. On a football team, its not the strength of the individual players, but it is the strength of the unit and how they all function together.
Building a team isn't easy, but some organizations know the best way to go about it. It starts with coaching and scheme, adding (but not overpaying) the right quarterback and then the offensive line. Next, a strong secondary followed by a stout and balanced defensive line round out the optimal foundation. Spend a little more for an x-factor tight end, and you have a team able to contend most every season.
Not every team in the NFL "gets it", but even some who do realize its harder than it sounds. You aren't in kindergarten where you can knock over your failed block tower and re-build it in a few minutes. Restructuring your team is very difficult because you cant start from scratch (0 percent) with plenty of freedom and flexibility to begin anew. You must start at 100 percent, and you can only remove a few blocks at a time. Which is why part of the experience of being an NFL fan is watching some teams get it and others struggle.
