The other side of her gap was probably inside Ran's clothes or something. And when the first person went to draw they'd end up groping her.
No, the idea is that the draws would be dispensed to Ran, and she would decide the matches and hand them back through the gap. Meaning they wouldn't be fair at all.
Updated
Well, then, time to draw contestants for the first match...That box looks suspicious, Yukari-san!Reimu?Ah...Yakumo Ran Termination NoticeA Yakumo Home-brewed SpecialHow do we determine who plays against whom?Through lottery.The draws had better be fair.Why, of course.Spirit Sign "Fantasy Seal"G. A. P. ♥ BOXGyaargh!!Ran-sama!?