I agree with what you are saying, I think the Rams made the hard decision of "do we stay with Bradford who when healthy can make all the throws or do we bring in a guy who may or may not be as talented as him but he can stay on the field and save us money".
To be honest I think Foles can thrive in our system due to his mobility and he has a pretty good arm.
Sam could possibly thrive in Chips system as well as you mentioned due to the fact they operate out of the shotgun. I personally believe he is future trade bait to get Mariota, just my thoughts lol
Believe me I wanted to see Sam come back healthy and do well with the weapons we have now. But due to injury i think it was best to move on and get what we could for him. Which in this case was a solid QB draft picks and saving on cap space to make moves. So solid trade.
Now lets draft well get some O Line in here and try and win the division this year!!