The talent level on the team declined significantly
The Pats struggles aren’t a mystery, they are a very mediocre team in terms of talent. This is what a mediocre team looks like. Every level of D is average or bad and there are too many declining players and gaps in depth on offense .
Get dominated by a mediocre Titans team, now struggling early against an outright bad Jets team.
Fans don’t like to hear it because a lot of the faces are the same as the previously great Pats teams but too many key players have left without replacement, too many key players have declined with no young depth to replace them. And the D has been shaky in the front 7 for much of the past decade (with one or two years of good play when health and veteran stop gaps break in the team’s favor)
This is a team built to put pressure on the opponent by scoring and moving the ball easily. Their disastrous offseason and wasted draft (even if you like the picks, they’ve had almost no return on those picks) have crippled the offense which ruins their strategy of winning by driving consistently on offens
This team, for a decade or more, has flowed through the offense. They can’t do that anymore which is why you see so many stalled drives and need for trick plays. The talent on offense just isn’t where it needs to be. It seems that Brady’s career is going to end with a whimper given the decline in take the around him. They’re good enough in coaching and at QB to win a bit more often than they lose but the days of being a premier contender are done. Still, we’ve seen mediocre teams win the Super Bowl (Giants most notably) so all is not lost. Just very unlikely.