Is this based on any particular research?
4000 extra tickets would have been sold because they were £5 each cheaper? Seems a bit fanciful to me, agreed, a fiver is a fiver, almost a pint and a half of lager, but I can't see that being enough to make someone decide to go to a football game...
Seeing as you are choosing the dearest ticket price in the Amex, you might be interested to know that Birmingham, Ipswich, Leeds & Leicester all have a more expensive 'dearest' ticket price, and none of them include subsidised travel.