In a league built on the principles of parity, the New England Patriots have been the one major exception: for the last nineteen years, the team has continuously been in the hunt for the Super Bowl and despite salary cap and free agency won six titles since the turn of the century. The Patriots did this not only by having the greatest quarterback of all time in the fold, but also by finding a way of keeping the roster quality high despite constant turnover.
How did New England accomplish that? By keeping the core of in-house talent intact, adding veterans on high-value contracts, and regularly finding contributors through the draft and rookie free agency.