Not sure if someone already considered this angle... Is it possible that the "powers that be" are a little unhappy with the way the offense built around Smith has been performing. Maybe, just maybe, the signing of Carr is an insurance policy so the organization can go back to a more QB-friendly situation... and quickly.
It takes a long time to establish an offense - if you don't have a QB to build it around. We've heard that our O-Coord is really good at building an Offense around his QBs. I have a sneaky suspicion that we will see a lot of West Coast type plays worked into our Offense this season.
The two systems aren't "mutually exclusive. Besides naming conventions, we can easily work many/most WCO plays into our current offense. This would help Alex too, but I think it's geared towards our running game, and Carr...
Remember - Carr is a WCO QB. He was drafted as such. The Houston team he played with tried hard to get it working - but they were an expansion team with no talent around him. They finally got a RB a couple of seasons ago, but by that time his confidence was gone in the organization and the talent around him, and perhaps himself.
I see his signing as similar to the Steve Young signing (not saying he's as good as Young), but, of course, there isn't a HOFer in front of him. Regardless, I think this is a good move.
Would love to see the WCO back...!!!