Notts County boss Shaun Derry admitted to feeling "frustration and anger" after his side lost 3-2 at home to Shrewsbury.
Shrewsbury midfielder Jon Taylor's double over 10-man Notts helped earn boss Mike Jackson his first victory as boss.
Jackson, who on Friday was appointed as Shrews manager until the end of the season, had been in temporary charge since January 22 following the departure of Graham Turner.
But Taylor's strikes, either side of James Spencer's sending off for County, and David McAllister's late winner earned the Shrews' first three points since New Year's Day despite being 2-0 down after 13 minutes.
Derry said: "There's frustration and anger, all the things that come with losing a 2-0 lead at home against a relegation rival.
"Every time we've done well since I've been here it's because we've followed the rules that I put on them.
"As soon as they decide to become 11 individuals again that's where the problem is."
On the red card for Spencer, Derry added: "You know what he's going to do on the training field and I didn't think for one minute he would be doing anything like that.
"That's the question that I have to ask him because I'm sure he doesn't even know why he did it now.
"In the heat of the moment people do silly things but you have to harbour those frustrations.
"If you're getting hit by a centre-half you can't do that. He's let everyone down.
"At this level you're bound to get knocks and elbows from the back."
Jack Grealish opened the scoring after eight minutes for County before being felled by Shrews captain Tamika Mkandawire in the penalty area - Alan Sheehan stepped up to slot home his third goal of the season from the spot.
Taylor reduced the Shrews' arrears in the 32nd minute and the visitors' hopes were given a further boost when Notts' striker Spencer was sent off just before half-time for elbowing Connor Goldson.
Taylor then got his second goal of the game after 67 minutes before McAllister converted a scrappy winner three minutes later.