Assuming the Rams defense plays as they are capable, if the offense can score only 5 or 6 more points per game than last year, they'll probably win 8 or 9 games. For one thing, the extra scoring will mean, in most cases, that the offense is on the field longer and the defense shouldn't be exhausted by the beginning of the 4th quarter.
Can they score 5 or 6 more points per game? While that is a big increase, I think it is likely relative to how poorly they scored last year. Just having Whitworth, and a competent Center, and some WRs who will catch the damn ball will make a big difference. But adding some good offensive coaching and schemes, and adding an element of offensive aggression, will help as well.
Of course, it still comes down to Goff executing. My guess is that he will do pretty well; I don't see his performance last year as badly as do others. He can't protect or catch or run the ball by himself. Much of what happened to him was on others. Some was certainly on him, but good grief he was a 21 year old rookie in a piece of crap offense with Junior High coaching and scheme.