Its actually quite massive. Look at the attendance below. The first match was against 8th ranked team of other group. I won the last 3 matches before so my fans should be stable and supporting me.
The Banton Royals are the top team of other group and still havent lost a match.
Finally the 'roos they dont show up to matches as they will be a bot soon and only have 3 players left. My arena size changed in between but the percentage was roundabout 80% vs ALBA, 98% vs Royals and 75% vs 'roos
26.02.2011 Flying Kangaroos 6781
19.02.2011 Banton Royals 8061
12.02.2011 ALBA LICHTENBERG 6697
my conclusion is that the opponents team fans which are suppose to travel with them can make up to 20% of total spectators or casual fans are interested against Top teams of your group.