I've been noticing this a lot too. Just today I was fighting someone who had Sage Naruto in slot 1 and I had Darui in slot1 and Mabui in slot 3. He has more power and higher initiation than me so I waited for him to cast Rasen Shuriken on my Darui and I Queued up my Mabui as soon as it hit my Darui and he was also getting a couple of chases off of it. Then his Naruto proceeded to standard attack me before my Mabui even cast her mystery. This was on SWB where you fight in x1 too.