Gary Johnson bemoaned his side's first half performance as they slipped to 4-2 FA Cup first round defeat by Maidstone United at the LCI Rail Stadium.
The National League side side took a three-goal advantage into the interval but were reduced to ten men 11 minutes after the restart.
Kevin Dawson, who was himself sent off in the closing stages, pulled one back for the Robins but boss Jay Saunder's extended his side's advantage with a fourth almost immediately.
An own goal by Alex Finney gave Johnson's side hope but in the end, the Kent side ran out deserved winners.
"They were two leagues ahead of us in the first half and there wasn't an individual playing their normal game.
"The first half was a very poor performance.
"You do have to question the commitment after a game like that but I know the lads inside out and I know that they don't purposely go out, not to try.
"They wouldn't be anywhere near one of my teams if they went out there and not try. It can look like that, but it was very poor defending and we couldn't take our chances.
"They took theirs, and to be 3-0 down at half-time left us with "a mountain to climb. I'm disappointed with how the whole day went.
"At 4-2 down and with them down to ten men, it should have been game on. We had unbelievable chances to set up a grandstand finish but we didn't have the quality to take them.
"I have no complaints with Kevin Dawson's sending off because it was a late tackle.
Johnson was himself dismissed two minutes from time for a gesture made towards the assistant referee.
"I had a chat with the referee and put my case across. I'm the first to hold my hand up if I've done something wrong but he's misinterpreted something I did with my hands.
"The referee thought I had put two fingers up at the linesman, but I've never done that in my life and had the linesman had made three mistakes I wouldn't have been sent off.