This latest capitulation followed a lame 1-1 draw at home to North Macedonia last week.
Herzog said: “We just aren’t professional enough. We talk about dreaming of doing it and then make stupid mistakes that cost us the game.”
It was a sloppy last-minute pass by Charlton midfielder Beram Kayal straight to a Slovenian forward that allowed the hosts to win the match, when Benjamin Verbic headed home unmarked from the ensuing cross.
Verbic had put Slovenia ahead just before half- time, but two splendid long-strikes early in the second half from Bibras Natkho and Eran Zahavi put Israel 2-1 up, before Roman Bezjak ran through a gaping hole in Israel’s defence to equalise.
Zahavi has now scored a remarkable nine goals in the Euro 2020 qualifiers. But it looks increasingly unlikely that he will grace the finals next summer.
Israel are now fourth in Group G behind Poland, Slovenia and Austria. Two points behind Austria with four games remaining.
Israel will need to win in Vienna next month to overhaul Austria, if they want to finish in third place and reach the play-offs.