The win sees Napoli sit third on the table, six points behind leaders Juventus, while Lazio have one win from their past nine domestic outings – leaving them in ninth spot.
Benitez praised his side for persevering in difficult conditions and hailed their second-half efforts, as they snapped a two-match losing streak in the league.
"I felt that the poor performance in the first half was the groundsman's fault," Benitez said.
"The pitch was a bit bumpy and we couldn't play as we wanted. It wasn't easy.
"Both teams suffered when they had to press.
"Then in the second half, when they were a lot more tired, it was easier for us to keep the ball and play."
Benitez said his side defied the conditions to remain organised, which saw them score four goals on the road.
"Today we stayed tight and compact and if the pitch is bumpy and we have to press high up or pass the long ball, it's easier for us and I think we have done it very well," the Spanish tactician said.
"But the most important thing of course was our attitude, intensity and also tactically wise we did a good job.
"We might see this game under another perspective but ultimately it's not important.
"The main thing is that we have scored four goals away from home against a good team that work tactically very well, who have a good manager and good players.
"Today we have done our job pretty well, especially in defence.
"We got it wrong when conceding the second goal but I think that in general we have performed well tonight."
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