Just remember that Effort and Enthusiasm are actually two seperate (but related) concepts. They also (anecdotal) have different impacts to different parts of the game.
Effort is what your team will put in for that particular game .
Enthusiasm is based on previous games effort. More effort in previous games results in lower enthusiasm moving forward.
SO if your team's Enthusiasm is 5, if you put in Crunch Time Effort, it doesn't actually 'magically' make your enthusiasm 7 or 8.
HOWEVER, what most people do, is in order to measure the equivilant effect of Effort on a game, they talk about it in terms of a resultant Enthusiasm value.
This isnt strictly true, but it does help give you a measure of what your team is going to be capable of and a bit of a formulae for working out how good your team is going to be.
As i mentioned previously, there is anecdotal evidence floating around the traps that suggests that Effort and Enthusiasm result in different impact to your team. From what I can remember, Enthusiasm makes your team better overall (eg: A bit like Game shape on individual players).
Whilst it is believed that Effort will increase specific items more than other items. Fouling, rebounding, aggresiveness, stealing etc.
Generally ive noticed games where I CT, the guys do foul a bit more, crash the boards a bit more, get more steals, and there is probably some negative to this as well.
So yer. hope this helps.