Sasuke is just there to back Itachi up and to keep Kabuto from sealing him. This fight is Itachi vs Kabuto. I'm sure Sasuke hasn't even shown half of his EMS powers, so his upgrades will all be revealed in his next battle. Either Sasuke and Naruto vs Tobi or Sasuke vs Naruto. Who agrees?
I'm no Sasuke fan but this is reasonable