Mazzarri left the Stadio San Paolo in May to take up the top job at Inter, having led Napoli to second place in Serie A and a subsequent return to the UEFA Champions League.
Napoli are third in the league in the mid-season break, but have accrued three more points than after 17 games last term, have a better goal difference and are five-points ahead of Mazzarri's new club.
Benitez's side were also cruelly denied a spot in the Champions League knockout round, missing out only on goal difference after picking up 12 points in a group including Arsenal and Borussia Dortmund.
And De Laurentiis is delighted with the strides his team have made under the Spaniard, pouring scorn on bigger sides who he believes are underachieving.
He told Radio Kiss Kiss: "I have nothing against those who gave a great deal to Napoli, but we wanted an international choice and a coach capable of giving our football an identity like the most important clubs in the world, with a complex 4-2-3-1 system.
"Don't forget we have three more points this season than we did last year, even though we also had to play the Champions League. Last term we abdicated the Europa League in order to dedicate our focus on Serie A.
"Our objective is to keep reinforcing Napoli with Benitez and give him time to reap what he sows.
"No offence, but I don't see other more prestigious clubs doing that well."
Napoli will hope to reel in Juventus and Roma at the top of the table when they resume their Serie A campaign at home to Sampdoria on Monday.
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