User blog comment:Xilinoc/Ch. 566 (not out yet, but dis gon b gud)/@comment-8669536-20140129172732/@comment-1747976-20140202014529

Definitely, calling out the name of one's zanpakuto without a release command is a sign of an increase in power and being more in tune with one's sword(ala sword zen). I remember when Renji did it with Zabimaru during the SS arc. I know it to be so because even Byakuya asked him how he did it or how he increased in power and ability without him knowing... If I can remember, Renji responded saying to him that he was either too busy looking down on his subordinates to notice or not concerned... In any event, we'll see....