I like your thinking. Yasopp is a sniper who maybe is not the strongest in the short range but is highly deadly in the long range. This gives him extra points to his power. He can be like a maestro of the battlefield from his sniper nest, taking down every threat around and getting rid of strongest opponents faster than short range fighters.
With Usopp and Yasopp providing the long range support for the frontliners, and Sanji setting up the field for Usopp to deliver the final shot.