From the Lombardi clip, "the #1 thing you have to do on D against Shanahan's outside zone run is set the edge, they couldn't do it."
I asked this a couple days ago. How are the Smiths vs. the run? Someone said they are just fine vs. the run. Doesn't look like it. Especially not vs. SF. They did not set the edge. This was a problem in their run D all season but no other team went after them the way SF did. Ketchman had a comment on his blog this morning. GB has a problem on the edges when it comes to stopping the run because the Smiths either "can't or won't set the edge". He thinks they're exclusively pass rushers and not 3-down players.
I don't have access nor the time to review tape (deleted Sunday's game) on them but this is two sources who know a lot about football saying the same thing. I know, I know. They're the least of the D's worries. But that doesn't make the problem go away. Especially if we're trying to figure out how to beat SF.