Oldham boss Lee Johnson admitted his side's first-half performance in their 2-1 home defeat to MK Dons was "horrible to watch".
The Dons went into the break with a two-goal cushion courtesy of George Baldock's first league goal and Izale McLeod's eighth of the season in all competitions.
Johnson made all three substitutions at the interval and he was rewarded after 57 minutes when former Don Charlie MacDonald headed in Gary Harkins' corner.
Latics pushed for an equaliser but ultimately paid the price for a first-half display that left Johnson having to apologise to the club's fans.
"When you send out your team you expect them to at least do the basics," he said.
"It was very poor from the first minute and horrible to watch. Everyone was moaning and Boundary Park wasn't a nice place to be.
"For some reason the players just weren't right, so I can only apologise for the first-half performance.
"I had no choice but to make all three substitutions and although we had a go in the second half, it was too little too late.
"Maybe we could have equalised, but we didn't deserve anything after the first 45 minutes.
"We were totally outplayed and that's very disappointing for a manager because you lose a bit of faith in people.
"It worries me that we seem to have a group of players who will pick and choose when they have a lively day.
"Whenever we put in a decent performance, we then go and chuck in a game or a half like that."