Terry Brown was left fuming after watching Wimbledon lose 2-1 at Hereford, who had not tasted victory in their previous 10 home matches.
Goals from Lyle Taylor and Tom Barkhuizen secured all three points for the Bulls, while Jack Midson's strike was scant consolation for Wimbledon.
And Brown berated his players for allowing Hereford to steam into a two-goal lead.
"There is no way in a million years you can give teams a two-goal start whoever they are, even if they have got a great defence or a defence that is conceding a lot of goals," he said.
"When you do that you put yourself under terrific pressure and our problem is we are not keeping enough clean sheets.
"We're not defending well enough as a team and that starts at the front. You only have to look at our goals against column to know that that is where the problem is. We would have had to score three to win at Hereford and that is not good enough."