User blog comment:B214/Volume 17 spoilers./@comment-24053170-20140220004506/@comment-24053170-20140220023821

I didn't say he was stronger, I just said he is so big that finding a place with enough room where he could train with him would be a challenge. great red is about 200 to 250 meters long, while Migardsormr is 500 meters or bigger. so finding a place were issei could train with him would be hard.