Brees is hoping to return from thumb surgery sooner rather than later, but Bridgewater’s performances have at least given his recovery some breathing room.

Kyle Allen, Carolina Panthers (4-0)

After Cam Newton sprained his foot in Week 2, the Panthers turned to Allen, their second-year man. He did well in two appearances last year and has created more buzz this season, throwing seven touchdowns in four wins without being intercepted.

Newton will regain the starting job when he returns, perhaps in a few weeks, but Allen is at least making it a debate, something few would have expected when the season started.

Jacoby Brissett, Indianapolis Colts (4-2)

It was a tall order to replace Andrew Luck, who shockingly announced his retirement in August, just two weeks before the start of the regular season. But Brissett has been explosive, with 14 touchdowns, one off the league lead, against three interceptions, a clear improvement over his 13 touchdowns and seven interceptions in 2017, when he subbed for an injured Luck. He was exceptional on Sunday, with four touchdown passes, to beat the Texans and take a half-game lead in the A.F.C. South on a day when the team’s running game stalled.

Ryan Tannehill, Tennessee Titans (1-0)

In midgame last week, the Titans sent Marcus Mariota to the bench and turned to the veteran Tannehill, who was most recently a starter with the Dolphins last season. The move has looked inspired so far: Tannehill was 13 of 16 against the Broncos last week and 23 of 29 in a start against the Chargers on Sunday. He has played only a game and a half, but his adjusted yards per pass figure is 9.0, trailing only Patrick Mahomes, Kirk Cousins and Russell Wilson this season.