User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-2600:1702:3600:12F0:1DB7:CCBE:4F4:B192-20190207160114/@comment-37222160-20190207185047

Even in his first match with Sairaorg, it became apparent that Issei was stronger than Rias. Because Rias couldn't handle Regulus. But Issei fought and defeated him both Sairaorg and Regulus. That's why Issei has already surpassed Rias because of his great potential.