Here is what I got from support some time ago

12/01/17 11:28Support
Good day,

It's based on guild fan rankings. The guild must have less than 20% difference.

Regards,
The Rugby Manager 2 support team

Using this and your two guilds current fan bases it appears there is an inconsistency. Their average fan base is 186,888 and yours is 143,351 which is a difference, using the larger number, of 23.3%. Now, if any teams have joined or left either guild those numbers could be off but if there have been no changes then it is not consistent with what we were told some time ago. And remember, champ level means nothing in pairing.

I got the .67/1.5 number maybe 18 months back; the example given does fit the parameters given to me.

20% is not enough information. As is it 20% more than the base, or 20% less?

We would assume 20% of the larger fan base to give the largest variance. If 20% of larger is used it would be 25% of the smaller. Thus if a guild had an average of 100k fans then they could, according to the support ticket I have shown above, pull guilds in the 80k-125k average fan base range.