The Spaniard felt that his players had actually done well on a dreadful playing surface in Sardinia but acknowledged that a point was not enough for the title-chasing Partenopei
The Partenopei fell behind to an early goal from Nene, after a slip from right-back Christian Maggio, but quickly drew level thanks to a Gonzalo Higuain penalty.
However, despite their best efforts, the visitors were unable to force the winner they needed to draw level on points with second-placed Roma - and Benitez felt there was no doubt as to where the blame lay.
“In all honesty, it was difficult to play and move the ball around quickly on a horrible pitch,” the Spaniard told Sky Sport Italia.
“We created more chances than Cagliari, but it was not sufficient, as we should’ve scored two or three goals.
“It was a very important match for Cagliari in front of their fans. In theory, a draw here is not a bad result, but it is for us because we’re chasing the top of the table, even though it was very difficult here.
“The ball did not roll evenly, so we had to go for long passes and this created a gap between attack and midfield."
Napoli now sit two points behind Roma, and a further five adrift of leaders and two-time defending champions Juventus.