I think the other thing Young talked about was more significant. He said the 49ers were playing single high safety man over. Meaning, they only had 1 safety and man coverage on the WR's. Said he felt like he was in the '80's again because modern defenses can't play this coverage most of the time or they'll get beat. But with the Rams, the 49ers felt no threat of getting beaten by the passing game.

The receivers only had to beat 1-on-1 man coverage and they still couldn't get open or beat the defense over the top. So, the 49ers were able to just stack the box all night.

It's probably a combination of things but it boils down to the passing game for the Rams SUCKS. The QB doesn't have the arm or overall talent, the line can't block quite well enough, the receivers can't win 1-on-1, the offense itself is horizontal, predictable and archaic and the HC is in over his head.