Real were beaten at Real Betis on Saturday in LaLiga before managing to defeat Atletico Madrid in the first-leg of their Champions League round of 16 tie 2-1 last night.
Speaking on El Larguero, Benito said: "(Kylian) Mbappé and Vinicius have not fulfilled the minimum services at a defensive level and the team is suffering.
"Carlo Ancelotti has spoken precisely about that. That when they (Mbappé and Vinicius) do a good job, the central midfielders don't have to jump forward so much and can join up with the central defenders, which makes the team less vulnerable. As happened on the day of Manchester City.
"This year, except for very specific moments, Real Madrid is having problems defending forward in the opponent's half and against high-level rivals, teams grow, dominate you and subdue you."