The Reds were hardly in the game during the first half and trailed 2-1 and although the arrival of captain Steven Gerrard just before the hour-mark changed the momentum he could not produce another miraculous recovery.
Rodgers had made six changes from the team which demolished Norwich 5-0 last weekend but tellingly he left experienced players like Gerrard, Jamie Carragher, Lucas Leiva and Stewart Downing on the bench.
Three changes were made to the back four - although it still had Slovakia international Martin Skrtel at its heart - and they looked helpless to stop Matt Smith scoring twice in the opening 45 minutes.
Rodgers said he wanted to give younger players experience - only Skrtel, Suarez and goalkeeper Brad Jones were aged over 23 - but when the result went against them it was them he criticised.
"We are bitterly disappointed. We started the first half poorly and we started the second half and got punished," he said.
"We've got a big week of games but our mentality in that opening period was poor and it ended up costing us.
"I was disappointed with the young players today [Sunday] I've got to be honest.
"We are trying to give them experience and let them see what it was like to play for Liverpool.
"It is not just about playing for Liverpool, you have to be competitive and be part of a group that is going to challenge for trophies.
"I thought how we reacted to that and how we performed, knowing that is what we are looking for, was disappointing.
"It is not enough to play for Liverpool and get up for the Arsenal and Manchester City games (later this week) because if we are going to win trophies you need to be able to come to places like Oldham and win and we weren't good enough for that.
"We were just too much on the back foot early on, you really have to be aggressive.
"These are different games to the Premier League: Premier League games are nice, you go in and teams will pass the ball and give you time to get your shape.
"These games are a different type of football, you have to roll your sleeves up be strong and aggressive and unfortunately for us there were too many who were.
"It is just a different type of football where you have to stand up and be counted.
"It is great to put young players in but you have to have personality and the young players disappointed."
Asked whether younger players were too cocooned in a Premier League environment Rodgers replied: "They will never get comfortable, you can't be comfortable at Liverpool and they are never allowed to be."
A couple of weeks ago, after an insipid first half in defeat at Manchester United, Rodgers rejected suggestions his side lacked - or needed - more of a competitive edge.
The way Smith dominated the defence in the first half said otherwise but Rodgers said problems were deeper than that.
"It was across the board, we didn't press them well enough from the front," he added.
"You have to stop the ball at source. The ball comes into the big guy (Smith) but you have opportunities to stop it before it does and the second goal we never tracked the runner.
"The full-back goes forward and gets the cross in. We talked about that at half-time and within five or six minutes of the second half the same full-back scores with a header."
Either side of Smith's first-half double Luis Suarez scored his 21st of the season but early in the second half Reece Wabara headed in Oldham's third and Joe Allen's first goal for the club proved little consolation.
Despite the win Latics boss Paul Dickov's future remains under threat after one point from eight games has left the club dangerously close to the League One relegation zone.
Chairman Simon Corney refused to be drawn on the manager's future despite growing speculation he could be poised to wield the axe and Dickov, who last month saw most of his backroom staff sacked, was not keen to talk about it, saying: "Let me enjoy this first.
"I have spoken to Simon and it's not been mentioned - if something was happening I would have thought he would have told me.
"There are a lot of things that went on that me and Simon need to talk about.
"You can spit your dummy out or you can roll your sleeves up and get on with it and one thing I will always do is work hard."
On the result itself he added: "I'm proud of the players and the performance they put in.
"To put that in against a team of world-class players was fantastic.
"I know what they are capable of. I just thought the desire they had to win the game was the reason we won it.
"I've won a European medal, I was involved in FA Cup finals, played for my country, scored at Wembley but after everything that has gone on recently that was right up there at the top."