The whole 3-5-2 started when we wanted to counter Napoli's strengths last season in that 3-3 draw.
When playing shite sides like Genoa, the 4-3-3 puts them under much more intense pressure allowing us to dominate higher up the pitch and make many more dangerous passing moves. 3-5-2 against defending teams makes things too crowded, particularly when you have pseudo-wingers (and players in the case of DC)