I'm not sure that having fans of the 4 main Dublin clubs all in the one stadium together at the same time is a wise idea. I can imagine it would give AGS palpitations for a start.
What I do think would be worth exploring would be Bohs looking to host one of their home derby games against Rovers at the Aviva. Do a deal with the FAI so it won't cost a fortune if the crowd isn't huge. But given that Rovers have 7-8,000 sell-out crowds at their bigger games, and the big nuber that Bohs took to last year's cup final, you'd expect that a Bohs-Rovers derby in a big stadium with some proper marketing could draw 15,000+ ? Make it on the opening weekend of the league and you'd hope it would draw more again. 15,000 tickets at €15 for adults would be a big pay day for Bohs, and help more of their fans see the game as well. Or make it €10 for adults in a promo to maximise numbers, and try to get as many neutrals and randoms along as possible.
Bookmarks