Marek Hamsik netted a brace and Gonzalo Higuain and Manolo Gabbiadini were also on the scoresheet in the huge UEFA Europa League first leg quarter-final win.
Benitez was full of praise for his team, but was unwilling to describe it as their best of the campaign.
"A spectacular performance. I've said for a long time this squad has quality, character and professionalism, all of which were on show tonight," he told Mediaset.
"We put in great games against Roma and Lazio, yet played worse against Fiorentina and won 3-0.
"Tonight we combined the performance with the result, showing players who work for each other and this attitude can make the difference."
Napoli's players were put into a training camp after their loss to Lazio in the Coppa Italia on April 8.
Benitez has accepted that decision, but believes some of the criticism of his players has been unfair.
"We all know where this team started from and there was a bit of a slow down this year, but we did play well and just made some individual errors," the Spaniard said.
“What I do not like is hearing people say the players are unprofessional or undisciplined."
