Danny Wilson said Chesterfield were the architects of their own downfall at the Proact, where his former club, Sheffield United, won 3-0.
The Spireites were at fault for all three goals, and Wilson lamented his side’s decision-making against what he called a good side.
“The goals came from our mistakes,” he said.
“Up until the first goal there’s nothing in the game, we haven’t had a shot on goal, they haven’t, it’s a battle in midfield, and then we don’t pick up from a corner.
“The second one was just a massive mistake by Tommy (Lee). You can’t give a team with that calibre any kind of start.
“We were fortunate the other week when we started poorly against Port Vale and came back, but they’re a different kettle of fish, United. They’ve got some good players, experienced players.”
Wilson was disappointed that Chesterfield showed none of the spirit that helped them beat Barnsley with 10 men a week ago.
He said: “Overall, irrespective of how you play, what system you play, you’ve got to be out there doing all the things we did last week.
“At Barnsley, we were tight, disciplined, strong, competitive, and a lot of that didn’t show today. We paid the price for it.”
A derby defeat, in such a disappointing manner, might ordinarily be reason enough for a lengthy post-mortem in the dressing room.
But Wilson is keen to move on to focus on the next challenge, a relegation six-pointer with Doncaster at home on Tuesday night.
“We’ve got to have a good look at ourselves and move on to Tuesday.,” he said.
“If we dwell on it, it’s going to make it worse. I could stay in there for two hours and talk about what went wrong, but it doesn’t serve a purpose.
“The bigger picture is that we have a big game on Tuesday and, prior to today, we’ve only lost two in 11. We’re not on a bad run. People should remember that.”