Thomas Baillie admitted Kettering Town “destroyed themselves” after they were thrashed 6-1 by Weymouth.
The Poppies, who are on the brink of relegation from the Evo-Stik Southern League Premier Division, took an early lead through Lewis Wilson at Corby Town’s Steel Park on Wednesday night.
But from there, the night took a turn for the worse as the Terras ran riot to go into a 4-1 lead before adding two more late on to inflict even more misery on the troubled Poppies.
Baillie was forced to change his starting line-up an hour before kick-off with defender Henry Eze missing a train, which resulted in him arriving just minutes before the game started.
But the Kettering manager was unable to justify his team’s display and blasted them for making “schoolboy errors”.
“Being really honest, it was embarrassing towards the end,” Baillie said.
“We had a few chances in the first half and we took the lead. And even at 3-1 down at half-time we thought we could get something from it.
“But we have destroyed ourselves at the end of the game. We can’t justify what happened in the final 10 minutes.
“Regardless of what anyone gets paid or anything like that, they were making simple schoolboy errors that some 12-year-olds wouldn’t do.
“They were on the dressing-room afterwards talking about it and they know they have created their own downfall.
“Some of our players had a seriously poor night and it didn’t help with players missing trains and things like that. We had to change our team an hour before kick-off.
“It simply wasn’t good enough and that’s all you can say.”
The Poppies head to Redditch United on Saturday to take on the team who sit immediately above them in the other relegation place, although the gap between the two is a massive 18 points.
And Baillie believes there may have to be some “radical” decisions made after the miserable midweek.
He added: “I will speak to them all individually before Saturday. It is difficult to pick them up when they already know what mistakes they have made.
“I think there may need to be one or two radical decisions when it comes to what team we put out on Saturday. There are a couple struggling with knocks and we will need to think about it.”
The 6-1 defeat to Weymouth was witnessed by just 187 people at Steel Park, the third lowest ever attendance for a Kettering first-team home match.