The Vikings have succeeded despite having lost Adrian Peterson, last year’s leading rusher, in Week 2. He will not return until midseason at the soonest.

There is a lot more to the Vikings’ 5-0 start than the surprising offense. The smothering defense ranks first in the league in yards per play, both against the pass and over all, and has scored two touchdowns.

Minnesota’s play on special teams has helped as well. The Vikings have a league-leading two punt returns for touchdowns, by Marcus Sherels. Cordarrelle Patterson leads the league in yards per kick return.

Still, even though the Vikings are 5-0, not every indicator marks them as a superteam. Their schedule has not been brutal: Minnesota’s opponents were 11-12 entering Monday. The Vikings have played three home games, including one against the best team they have had to face so far, the Packers, whom they beat by only 3 points. Elite teams tend to win blowouts often, but the Vikings’ biggest margin of victory is 18.

A subtle worry is that the Vikings have recovered five fumbles and lost one. Years of data have shown that fumble recoveries are largely a matter of luck and tend to even out over time.

It is too soon, of course, to call the season off and award the Vikings the Vince Lombardi Trophy. There is a cluster of nine teams with only one loss. Oddsmakers have the Vikings as about the fifth favorite to win it all, behind four one-loss teams: the Patriots, the Steelers, the Packers and the Seahawks. The Broncos, the Atlanta Falcons, the Dallas Cowboys, the Eagles and the Oakland Raiders have also lost just once.