Yeah, enthusiasm and game shape are two commonly overlooked things. I didn't pay much attention to GS. If I have a guy coming back from injury with GS of 5 or lower, I like to give them run in that week's scrimmage, to help get it back for league play.
If you go TIE with enthusiasm, you team "banks" enthusiasm. So when you play a game on Normal or CT, their performance is enhanced. During the first half of the season, I tend to counter the importance of certain league games vs. Cup opponent strength in making enthusiasm decisions. It essentially resets during the All Star Game week.