User blog comment:B214/Volume 22 spoilers/@comment-28087053-20170114184806/@comment-31137559-20170209162001

They were talking about Issei and Vali in general, not dragons themselves. They meant Issei's rising influence and drastic changes in the world have been happening since Issei has been reincarnated as a devil. And also how Issei has been drawing powerful beings to him and the reason why all these things happened was because of Issei's influence. And all the strange phenomena(Fafnir and Asia's panties) are due to Issei and the Heavenly Dragon sealed inside the boosted gear.