Tom Brady? Overtime? An incredible Super Bowl comeback?

All the ingredients were there for a Super Bowl ratings bonanza. But early indications put the New England Patriots’ 34-28 overtime victory over the Atlanta Falcons on Sunday night down slightly versus last year’s game between the Denver Broncos and the Carolina Panthers. The game notched a 48.8 rating and a 72 household share in the metered market numbers, down from the 49.0 rating and 73 share for last year’s game, according to Nielsen.

The game’s wild ending — particularly for what looked like a certain blowout late into the third quarter, with the Falcons holding a commanding 25-point lead — brought in a huge audience. The game peaked between 10 and 10:30 p.m. with a 52.1 rating and 74 share, higher than at any point for last year’s game.

These ratings measure 56 major markets and represent about 70 percent of the country. More detailed ratings will be available Monday afternoon, but if the numbers are down, it will be the second-consecutive year that the Super Bowl did not set a new ratings record.

The Super Bowl concludes what was a troubling yearlong trend for the league. Ratings for the N.F.L. games in the 2016-17 season were down 9 percent over the regular season and 6 percent through the first three weeks of the playoffs, according to the research firm MoffettNathanson.

N.F.L. executives argued that the outsize interest in this year’s election was the culprit.