User blog comment:Jallu/2 Things!!/@comment-7658432-20130416100911/@comment-6963992-20130417002037

I don't think the Visoreds were Captains at Isshin's time. Shinji said he didn't recognize his spiritual pressure and Isshin only seemed to know about the Visoreds from a secondary source. Also,he wasn't shown during the shinigami meeting.