The Spanish tactician oversaw a brave performance from his Naples-based side, as they equalised with 10 men in stoppage time to extend their unbeaten streak to 10 league matches.
Sampdoria led at the Stadio Comunale Luigi Ferraris in Genoa with Eder's fine finish in the 57th minute, and were looking good value for the three points when Napoli defender Kalidou Koulibaly was dismissed in the 84th minute.
Benitez claimed Napoli deserved their equaliser - a buried header from substitute Daniel Zapata - and said he felt Rocchi did not perform to the Italian top-flight's standard.
"I think we had two or three clear chances to score in the first half despite not playing particularly well, while in the second half Napoli controlled the game and conceded against the run of play," Benitez told Sky Sport Italia.
"Without talking about incidents, everyone has an off day and we can say someone [Rocchi] had an off day today."
Benitez said given the changes to his injury-plagued team, preserving their unbeaten run - and denying Sampdoria a win that would have seen them replace Napoli in third spot - was a sign of their progression this season.
"We lost Michu, [Lorenzo] Insigne, today [Dries] Mertens returned and [Jonathan] De Guzman still has problems with his neck," Benitez said.
"The team is unbeaten in 10 games, so in the circumstances I'd call that positive.
"We knew from the start this could be a difficult season. We know our strengths and where we have to improve.
"I am optimistic for the future, but the team has to look at individual objectives in every game and not look forward to other fixtures or the table."
Benitez said he was pleased his side continued to attack at the death, despite being a man down.
"Sampdoria pressed us, played a very physical game and it was not easy, but even with 10 men we attacked to score and had more possession," he said.
"The first half performance may well be down to Samp, who pressed us all over the park.
"The game seemed to be under control until the goal, which I think was avoidable."
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