Richie Barker insisted Crawley fans should curb their expectations after the 3-1 defeat to Reading in the FA Cup third round.
The hosts, who had reached the fifth round in each of the last two seasons, made the perfect start at the Broadfield Stadium with Nicky Adams' 25-yard strike.
But two goals from Adam Le Fondre, the second from the penalty spot after Noel Hunt had put the Royals ahead, secured the Premier League outfit a place in the hat.
Barker was disappointed his side's hopes of another cup adventure were dashed - and frustrated that a section of the home support were chanting at him to "sort it out".
"We are disappointed, no matter how it started, because we played well. We deserved more out of the first half," the Red Devils boss said.
"We have given a Premier League team a real good go. We created enough chances to be ahead but their goalkeeper pulled off two or three really good saves.
"To put their goalkeeper under as much pressure as we did, for a League One team against a Premier League side, speaks volumes about the players.
"I thought we would create something every time we went forward. Their quality in the final third defined the fact we were a goal down at half time. Adam Le Fondre and Hunt are good players."
On the reaction to the supporters, who were chanting at Barker as his charges tried to find a way back into the game, he said: "You can't educate some people, can you?
"I will do the best I can and one day when I've gone, a bit like my old club, people will realise how well I did. The expectations (among some supporters) are ridiculous."