I will admit right off the bat that these are entirely cherry-picked stats. After the game, FOX's Curt Menefee apparently pointed to points allowed, sacks and first downs gained to describe this as the 49ers worst offensive performance since 1964. I did a little bit of research over at Pro Football Reference, and confirmed that. Well actually, it is 1963, not 1964.
The San Francisco 49ers offense had a field goal and eight first downs, and gave up six sacks. There are plenty of stats to consider in a loss, but points, first downs and sacks are often going to cover a lot of the issues a losing team might have.