City have a mountain to climb to make the play-offs now.
Colin Todd admitted that a top-six finish was nearly out of reach after Saturday's costly loss to Hartlepool at Valley Parade.
But he also urged fans to look at the "bigger picture" after the turmoil of last summer.
"Once again our home form has let us down," he said.
"But I would like to ask supporters where they expected us to come this season before a ball was kicked. I'm sure a lot of them would have thought we'd struggle.
"Some will say we aren't good enough but I think they have to look at the big picture.
"All right, I was a believer we could get in the play-offs and we could still do. But from where this football club have come from, we haven't done badly.
"Maybe if we had stayed down the bottom people might have thought we had done well to survive."
City could have revived their hopes by beating Hartlepool but rarely threatened to notch a second straight home win, despite an equaliser from Mark Bower.
They are now seven points off the play-offs and have dropped to 11th below Doncaster, where they travel on Thursday.
Todd said: "It was a game we couldn't afford to lose and a lot of the players didn't match the standards they have set. We were let down in a lot of areas. We had no tempo or cohesion in the first half.
"Doncaster is probably our final chance. But you know what our away form is like and I'd be very disappointed if we can't go there and show people that we are a better side than Saturday.
"It's another derby game and we have to try to salvage a bit more pride. If it doesn't happen for us, then I would have to plan for next season."
Marc Bridge-Wilkinson's one-month loan is due to run out after the next game. But Todd has indicated the midfielder, who was again City's brightest player, is high on his wish-list for a permanent move.
"I've already spoken to Mark about it. We're talking about planning for next season and he would come into that equation."
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