I just don't think we fans can get a good understanding of just how much a year in the league means to any player, let alone a QB, until we watch them play. Mannion is like a different guy from last year.
I'll reiterate something that GOOD talking heads on TV, and visiting GMs, college HCs, and other REAL football people say on TV shows: a rookie QB needs a year on the sideline holding the clipboard and learning. It's better for him and the team in the long run. QB may be the hardest position in sports to play. Of course, they all say this BEFORE the draft; and then afterwards some start throwing around the "B" word if a rookie high round pick QB doesn't start game 1.
I consider it a blessing if the 5th year player Keenum has really developed and is playing well (as he sure seems to be). And if 2nd year player Mannion is developing nicely and starting to show the talent that made the Rams spend a 3rd rounder on him (as it sure seems to be). It means that the whole load doesn't fall prematurely on Goff, and he truly doesn't have to play until his ready.
The trick is for Fisher, Snead, Demoff and Kroenke to resist what is going to be enormous media pressure to "prove" they were right in mortgaging the farm to draft Goff.
I'm not a Fisher fan, and I have little faith in the Rams at this point. I have hope, but no faith whatsoever. But it isn't hard at all for me to believe that Goff possesses high level QB talent and is going to be a very good QB in this league. That he needs more time doesn't bother me a bit; in fact I said from day 1 that it was unimaginable to me that he'd start before Game 4, and perhaps not until after the Bye week. But if the Rams are ready and built to win now, then let's use a QB with experience that can help us win now, rather than go through the birth pangs of earliest development of a rookie.
I think the Rams think they can win now (or perhaps Fisher thinks he MUST win now). If they didn't, they would have named Goff starter from the day they drafted him.