This study highlights the role of wave geometry, more specifically wave front-back asymmetry, for the technical design and operation principles for an oscillating water column (OWC) type wave energy converter WEC. For a selection of 12 sea-states and 8 wave models we simulate the relation between average front-back wave asymmetry and average generated hydraulic and electric power in a WEC developed by Waves4Power. We show, by large Simulink studies, that the degree of front-back asymmetry in the physical wave system can have considerable effects on the produced energy. The effect is mostly negative, with up to a 10\% energy loss for moderately asymmetric seas. For low-energy wave-states with long period there can be a small positive effect. In a special study, we investigate individual waves and how their degree of asymmetry affects the generated power temporally near the wave. The result shows both negative and positive effects, depending on the sea-state parameters.