How about 20 for being bang on down to 1 for submitting a guess?
I'm a bit concerned about the current 11 being too many points. It could move a team a ridiculous number of places up the league. Too many variables makes it a harder job to reckon up but how about:
10 - Exact (posted at least 7 days before the match)
7 - Exact (posted less than 7 days before the match)
6 - Up to and including 10 off.
5 - Up to and including 50 off.
4 - Up to and including 100 off.
3 - Up to and including 500 off.
2 - Up to and including 1000 off.
1 - More than 1000 off with submitted guess.
I think we need an incentive for early guesses so that is what I have proposed. We never really know the capacity, so I suggest we drop it. Everyone has the same chance so, with the incentive for early guesses, it should not be too bad.
I'll start a new thread with this so everyone can chip in.