Previous experimental works proved the ability of CECO to harness wave energy. This wave energy converter (WEC) is presently at Technology Readiness Level (TRL) three, where characterizing the energy conversion stages and evaluating the energy conversion efficiency is crucial. Therefore, in this work Ansys® Aqwa™ was applied to study a CECO unit and to obtain a detailed knowledge of its performance throughout the different energy conversion stages. The numerical model was initially calibrated with results from experimental tests and then used to simulate different configurations of the power take-off (PTO) system under a wide range of regular and irregular wave conditions. For most of the irregular wave conditions tested, CECO can absorb between 10 and 40% of the incident wave power and transmit to the electric generator up to 18%. Although the results reveal a high energy conversion efficiency, there is still scope for improvement of the device by optimizing the PTO. On these grounds, the ideal values of the electric generator damping coefficient are presented for different wave conditions, which allow to define an adequate control strategy in future works.