User blog comment:Gary299/High School DxD BorN episode 4 review/@comment-27989561-20150426034303/@comment-23853100-20150426042708

^^What B said. This is done to make Rose and Irina more important in the story, if everything is done in sequence, Irina and Rose practically has no role in BorN at all.

Look at it this way:

Volume 5 Main focus: Issei BB, Koneko and Kuroka, Rating Game. Base on this Rossweisse would appear for about 2/3 minutes only out of 4 episodes.

Volume 6 Main focus: Vs Khaos Brigade. Irina only appeared in the first part when she enters the school, the remainders are about the preparation for their next Rating Game and Ise x Asia thing. Irina only reappears when Ise goes berserk. So Irina would be about 0.5 out of 4 episodes.

Then Volume 7:

Main Focus - vs Loki, Akeno issue and basically preparation for Loki battle. Rose only helped in the initial and final battle with Loki so it'd be about 1.5 out of 4 episode. Same for Irina, she didn't even spy on the date so it's about like help fend off Hero Faction, fend off Loki and help defeat Loki. 1¼ out of 4 episodes.

Basically Ross would have like 1.5 out of 12 episodes and Irina would have 2 out of 12 episodes if the anime didn't rearrange things here. So people need to try and understand why TNK pull this off, just look at the current pace, Irina and Rose already appeared for about 3 episodes already.