I don't think Purdy is necessarily the problem, even though he's had a down year.
It's their ability to completely fall apart every single time they get into the red zone. As soon as they get in the red zone, the offense turns into a clown show. Penalties, miscommunications, bad throws, fumbles, dropped passes and on and on. Been a problem all season long and probably cost them a shot at the division.
That and the fact that their 3rd round kicker can't even kick as well as any run of the mill free agent kicker off the streets.