The exploitation of Renewable Energy Sources (RES) is critical to move forward and to aim for global sustainability. In this scenario, the development of devices able to take advantage of wave energy resources is continuously advancing. The basic methodology to acquire energy from waves is based on the identification of sites having high energy and the optimization of Wave Energy Converters (WECs), according to the sea states’ characteristics. The principal parameters which describe wave conditions are the significant wave height and the wave energy period, which allow estimating the respective average wave power, and the peak direction, which indicates the main incoming wave direction. However, these parameters give only limited information since the directional distribution of the different wave components is missing. In the wave spectrum analysis, the directional spread is a measure of the range of wave directions and states if wave components are coming from similar directions or various ones. Considering the spreading parameter is especially significant in directional WEC devices. The main scope of this paper is to highlight the relevance of directional analysis about wave and WEC device interaction. Therefore, considering the direction of every wave component, an accurate and detailed analysis can be conducted. Assuming Pendulum Wave Energy Converter (PeWEC) as a case study, the correlation between the performance and the omni- and uni-directional sea states is shown. Especially, the investigation results are focus on the influence that the variation of directional spreading value has on the PeWEC performing features.