Despite Latics facing a fixture pile-up that will put huge pressure on their League One promotion bid, Richardson named a virtual full-strength squad against the side sitting rock-bottom of League Two.
And the visitors showed the huge gulf in quality from the off, scoring three goals in either half to romp into the last eight of the Papa John's Trophy.
"It was a very professional performance," acknowledged Richardson, whose side had seen their previous three league fixtures all postponed due to Covid.
"As everyone knows, we've been without a game over the festive period, and you can train all you want.
"But we wanted to get distances into the players and get the relationships back up and running.
"We scored some good goals, we're through to the next round, so it was a good night.
"We had to look at the circumstances of late, the fact the lads haven't played for two and a half weeks, and we thought it was the right thing to do with the team selection.
"Oldham were obviously very mixed with their team selection, but you can only play what's in front of you and I thought the lads were very clinical and very ruthless."
The pick of the goals was number three, with Max Power - who had assisted the first two for Tom Naylor and Will Keane - firing in an unstoppable free-kick from fully 35 yards.
"We're going to be hearing about that one for some time aren't we?" laughed the Latics boss.
"I think he knew it was going either one of two ways...it was either going into the top corner or I'm going to get screamed at.
"Thankfully it went in, and it was one of many goals tonight we can be pleased with."
Gavin Massey made it 4-0 two minutes after the restart, with Gwion Edwards scoring goals five and six in the space of three minutes at the three-quarter mark.
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