User blog comment:Godisme/Deicide 2/@comment-452405-20100416005320

Wait new thought, Aizen says his soul has begun to understand the Hogyoku's will and is about to reconfigure, maybe having the Hogyoku fused with himself is taking some toll on his power if used too much, or as he's got closer to whatever transformation he's about to go through with he's needed to dedicate more energy towards controlling that meaning less to fight Isshin with.