By seeing how far it stretches the memory. If they don't win, they'll just be like Minnesota's great defensive teams. Everyone will forget them over time. Therein lies the rub. Regardless of the outcome, you can't erase statistics.
Statistics are it.
So they have. Baltimore gave up an average of 10.3 points per game, a record for a 16-game season. Since the AFL merger, the record for fewest average points allowed in a season is 9.2 by the Falcons in 1977. And, because of changing eras, it could be argued Baltimore's achievement is more impressive than Atlanta's. The Ravens held their opponents to 10.3 points at a time when the average defense yielded 20.6 points a game.