I agree that this may be the logic, however it doesn't make any sense to me
For one, how does a coach expect to win 10+ games and know that at some point he's going to make a QB change? I don't recall a QB change being made mid-season when the starter was playing well...
And two, how is Goff supposed to improve during the season when Keenum will get the majority of the snaps, and Goff will see no live action? And at best, he gets to play when Keenum and/or the team is losing?
Doesn't make much sense to me. If they wanted to take pressure off Goff they would have put him in the best position to succeed