A second team worth considering is the 49ers of the 1980s and 1990s. Like the Patriots, San Francisco had a run spanning 14 seasons in which it won several championships, five in the 49ers' case, with no Super Bowl losses. That team also had a regular-season record similar to the one the Patriots have had since 2001, winning about 75 percent of its games. (In fact, the 49ers’ best 14 regular seasons in a row covered a slightly different span, 1984 to 1997, and it’s the only such modern run better than New England’s.)

No player, however, played on all five 49ers championship teams. The run also spanned two head coaches, with Bill Walsh winning the first three titles and George Seifert winning the last two.

If anything, a better argument against New England is that Belichick and Brady aren’t enough to make the 2001-14 Patriots count as a single team. By this definition, the Steelers of the 1970s (who won four Super Bowls in six years) may be the best candidate. More than 20 players appeared on all four championship teams.

Those Steelers, like the Packers of the 1960s, also deserve credit for their dominance. They often won handily. On the other hand, the Patriots win some style points of their own. Every one of their six Super Bowls has been decided by four points or fewer, and five of the six — the two losses to the Giants, the wins over the Seahawks, Panthers and Rams — have involved nerve-jangling final minutes.

A loss to Seattle on Sunday would have left the Belichick-Brady Patriots with two distinct periods: the early one, when they won three Super Bowls, and the late one, when they kept losing heartbreakers. The win over Seattle changed the story.