That Mannion can be an effective back-up ought to be well on it's way to being determined.

Keenum is going to have to be paid in the $3.5 mil range per year. Mannion under $1 mil.

Cap management says that the Rams probably ought to let Keenum go and have Mannion as the backup.

None of this works anyway if Goff isn't the firm starter to begin next season (unimaginable he wouldn't be).
Doesn't usually work to keep the former starter around.

Besides, in this QB starved league, Keenum will get a shot to start somewhere.

I see the Rams making a major move to get a good WR in the offseason. My guess would be Alshon Jeffrey if they can get him.