United conceded two quickfire goals before half time and, despite an improved showing in the second half, couldn't respond to the two-goal deficit incurred, with Freddie Ladapo and Lee Erwin notching the goals.
"I'm disappointed with the result and I'm disappointed with the performance," he told The Iron PlayerHD.
"We didn't play as well as we have done this season. We didn't reach the heights and we didn't do the things well enough that we are good at.
"Unfortunately we lost control of the game for the last 15 minutes of the first half and it has cost us because Oldham have scored two in the period just before half time. It made for an uphill struggle to try and get back into the game.
"We were half a yard short of everything tonight - our decision making and pressing.
"They got their two goals while they had their momentum and, not for the want of trying in the second half, we just didn't get that break that we needed. We didn't really calve out any opportunities in the second half and it was a disappointing night for us."
The Iron's only other defeat so far this campaign, away to Port Vale, saw an immediate response in the shape of a 4-0 victory over Southend United in the next league game.
Speaking about looking forward to the next fixture to look to put things right, he said: "Of course, that's what football is about.
"No one said it was going to be a smooth ride from now until the end of the season. I keep saying that, even when we're winning games, I say how tough they are and tonight proved that.
"If we don't approach the game in the right manner - and I mean full-on, not 95% but 100% - then we can get hurt. We must learn from tonight.
"I'm not going to go overboard because the players have been superb this season, but we have to learn from the negative times."
The Iron made four changes going into the fixture, with Luke Daniels missing out following his injury, while Harry Toffolo was also absent. The United boss responded to the Norwich loanee's injury.
"Harry picked up an injury on Saturday in one of the late tackles which the MK Dons lad got booked for," he said.
"He's hurt his knee, but completed the 90 minutes. However, it's stiffened up and over the course of the night got quite sore and tender.
"We're hoping to only be missing him for two or three games, but it's still quite soon after the game. We'll have to wait and see until it settles down."
See much more from Graham Alexander and Stephen Dawson on The Iron PlayerHD.
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