FOXBOROUGH, Mass. — Thirty years ago, when restricted free agency kept N.F.L. rosters unchanged and parity was not the goal of the game schedule, it was customary for powerhouse teams to meet in the postseason year after year.

The familiarity of those matchups bred contempt. Rivalries grew fierce and the trash talking became personal. Every year it seemed the 49ers and the Cowboys would be snarling at each other, and if not those teams, then it was the Steelers and the Houston Oilers, the Giants and the Redskins, or the Broncos and the Raiders.

The N.F.L. is more antiseptic now. Taunting is actually a penalty. The recurring, heated and ill-mannered postseason matchup is less common.

Saturday’s divisional round playoff game between the Baltimore Ravens and the New England Patriots is the nasty exception. Ravens-Patriots may not be a historic rivalry, since the teams have met in the playoffs only three times since 2009, but they have packed a lot of malevolence in a short period.