3 reasons why the New Orleans Saints lost to the 49ers

The Defense
516 yards of total offense.
How can a team claim it can win it all with a porous defensive performance like its one displayed against the San Francisco 49ers?
Garoppolo was able to beat a team with his arm, for 349 yards and four touchdowns, and only threw one interception (leading to a Wil Lutz field goal).
The 49ers had their way on the ground as well, as they posted 162 yards on the ground and converted on half on their third-down conversions.
Speaking of it, the Saints played undisciplined defense by committing ill-advised penalties at the worst time, notably on third downs.
Particularly, on two third down plays, New Orleans had a phantom holding penalty leading to a first down and an unnecessary roughness call with C.J. Gardner-Johnson nailing Kyle Juszcyzk.
On that play, Garoppolo rolled to his right and threw a low pass to Juszcyzk as Gardner-Johnson blasted the fullback drew a flag.
It’s debatable whether that hit was helmet-to-helmet, but there was no need for the hit as Juszcyzk only needed to be touched down in that situation to force a field goal attempt.
That penalty led to another score, and on San Francisco’s game-winning drive, New Orleans was one play away from the win.
On 4th & 2 from their own 33-yard line with 0:39 left and trailing 46-45, Garoppolo threw a short pass to Geroge Kittle, and he was able to get into Saints’ territory.
Marcus Williams grabbed Kittle’s facemask for some reason and added 15 yards to the huge gain, making it easier for kicker Robbie Gould.
Gould connected on a 30-yard field goal as time expired, handing the Saints their third loss on the year.
Whatever gameplan Dennis Allen drew up leading up to Sunday failed miserably, and hopefully this game wakes this dormant defense out of hibernation.