I don't think McVay lost any faith in Goff, IMO, he realized his game plans were pass happy and McVay has adjusted accordingly and the addition of C.J. Anderson has a Godsend. Now because the Rams run so often, McVay lost faith in Goff? I don't think so, the offensive line wanted to run block and Aaron Kromer has had his unit ready.
The Ram passing game hinges off of play action, if you're not running, then you can't do play action, it's that simple. Goff will have to make some big plays against one of the best secondaries in the NFL on Sunday, all of us hope, he's up to the task.