Kind of a copout, that, isn't it, Ryman? You can always use 20/20 hindsight to decide if a move was "wrong" or "brilliant." The key is to assess the move fairly within the context it was made ... before the million other variable that end up affecting the eventual outcome come into play.
Shanahan's decision to go 3-4 was made in the broad context of what he believes is the best approach to winning a championship with this team. He clearly understood there would be transitional growing pains. He is one season into the process.
It's easy to look at it and say "he didn't have the personnel to run the 3-4." True. He did not. Truth is also that he didn't have the personnel to run a contending-level 4-3 either. The D here skated by on stats...rankings. It failed utterly on gamedays in crunch time with it's inability to pressure the passer and come up with turnovers and game-changing plays.
Shanahan set out to break the treading-water cycle the D here was in for so long and shake things up in order to play the kind of attacking D he (and many others) believe is the key to winning big in the NFL today. Frankly I think it was a bold as hell move. He KNEW he'd come into criticism from ... well ... guys like you.
I say power to him. The status quo was unaccepable. He set out to do something bold and is committed to doing it. I LIKE that in a new head coach coming to a team that hasn't won **** in 20 years.