South Africa lost 34-32 to Japan in Pool B last Saturday in the biggest upset in the competition since its first edition in 1987.
"We have become an ordinary team," former coach Jake White, who led the Boks to the world title in 2007, told French sports daily L'Equipe on Tuesday.
"Nobody fears us anymore. (Pool B rivals) Scotland have started to fancy their chances and it worries me."
White, who now coaches French Top 14 side Montpellier, added that South Africa's mistake was that they had underestimated Japan.
