If it isn't an illusion, then I think Aizen wanted to toy with them, and make them think that they were doing a good job.
Especially Hitsugaya. He has a tendency to like to mess with him. And as for Shunsui, well I'm guessing going toe to toe with him might require more of an effort than he put on with Komamora, Love, Rose and Lisa. As for Shinji's shikai, I think Aizen was aware.
Well for me, the story needs to progress, I want to know if Byakuya, and Kenpachi have been ****ed up by Yammy, or did they wtf pwn his lame ass already.