The Patriots, as they are presently constructed, will have to answer questions about going 19-0 every year before they play a single snap. They will be favored in most, if not all, of their games, and they will be asked if they think they can go undefeated to avenge a hard Super Bowl loss to the Giants. They probably do not want to answer questions like that, and suffering a hard loss to start the season ends those questions immediately. Bill Belichick must be secretly thrilled that his team lost, and he can start to focus on winning titles once again.
We get so excited about it
We get so excited about the Patriots going undefeated because we want to see the 1972 Dolphins cracking champagne as they celebrate another season where they are the only undefeated team in the history of the league. It is funny to watch because guys like Mercury Morris are happy to rub it in the faces of every team in the league, but some people hate those Dolphins teams so much that they root for a team to go undefeated without considering how hard that is to do. The Patriots could not do it because they lost their last game of the season the last time they flirted with perfection.
They can settle down
Let us assume that the Patriots were to start the season 3-3. They could easily go on a ten game win streak to enter the playoffs.
They would be the hottest team in the league entering the playoffs, and they would still be ranked as the best team in the league in nearly every power ranking index.
Losses like this one, against the Kansas City Chiefs, give teams a chance to settle down, work on their craft, and avoid talk of being one of the best teams in history.
You may be a Patriots fan who wanted to see your favorite team go undefeated, but you are more likely to see them win a Super Bowl now that they have lost. The distraction is gone, and Bill Belichick can keep his team from being unfocused and thinking they were so great. It is the perfect teaching moment for the Patriots coaching staff.
Will they rebound?
There is no doubt that the Patriots will rebound as everyone on that team, except for Tom Brady, knows that they are expendable. They know that they can be cut and replaced with someone else that Bill Belichick will coach up, and there are several players who will play harder simply to hold onto their roster spot.
That sort of fear makes teams play well, and it is a fear that is used by coaching staffs around the league. The Patriots have a habit of returning to normal quickly, and that should be expected in week two.