User blog comment:B214/Shin DxD 1 discussion/@comment-30230931-20180804194539/@comment-28884330-20180805031422

I don't have to be Ishibumi to know that Issei has most of the advantages, outclasses Rias and has the biggest chances.

This doesn't mean that Rias can't win or won't win since in a narrative pretty much anything can happen, but chances are not about absolutes. Issei having the highest chances does not mean Rias will lose, but he still has them.