The Patriots have seen this movie play out before, multiple times in the recent past. The defense opens the season by shutting down overmatched opponents, only to falter later in the year when the degree of difficulty rises.
In truth, that may be the case again this season. To this point the Patriots have faced three quality offenses – Miami, Baltimore and Detroit – and lost to two of them. The defense was largely uncompetitive in the Ravens game, and the lone win came against the lowly Lions and Jared Goff.
Otherwise, it's been a steady stream of backups (Mitch Trubisky, Jacoby Brissett, Sam Ehlinger) and otherwise misfiring offenses (Green Bay, the Jets twice).