So why not do that!
I do.
A1 Home team score
B1 Away team score
C1, 0.955^(A1-B1)+1

Of course your Inputs into the data cells must be in terms of actual points.
So with the ratings you originally came up with,Benny,you may have to multiply them by a factor of 10.
Sportznuts seems to have a much firmer grasp of what ratings are trying to represent!
Your ratings Benny,seem to get the teams in correct ability order,but don't really show the actual difference in ability between any 2 teams.
But that is fine for tipping competitions.

And Sportznut,It's nice to see someone remembers something useful that I have contributed,from amongst all the utter bull******** that have escaped from the clouded analysis of too much "Vitamin B".