Orochi's Samurai and Ninja needed to have been Stronger. The Pirate-Mink-Samurai-Ninja alliance was too overwhelmingly Stronger than The Beast Pirates and Orochi's forces.
Orochi's forces needed at least a few people who were on par with the Tobiroppo or people like Kawamatsu and Denjiro. So the Beast Pirates didn't have to carry the War so much. Or some Beast Pirates that learned more Sword Techniques or Ninjutsu.
