User blog comment:Jkphantom9/Volume 3 Episode 6 Preview/@comment-4010415-20151210011937/@comment-26397825-20151210012651

Cinder probably manipulated the matchups so the people who were actually stronger than Yang got taken out by each other and Mercury, so Yang would have to be the one to fight Mercury. They know RWBY has been getting in their way; technically they have taken Weiss out because we don't know how long she's going to be recovering for as her aura did drop to nothing while she was being roasted by a lava plume. If Mercury takes Yang out in a way that means she'll take longer to recover than a night's rest would take, then that's half of RWBY taken care of.

The other two would be easy picking for Cinder and Co after that, even if they got help from SSSN and JNPR, simply because RB wouldn't have the experience working with the others. Plus, JNPR without Pyrrha is kind of not on the same level as RWBY, and SSSN, while seeming strong, seemed to struggle in their round.