But while their Heineken and Amlin campaigns are now over for another year, Munster are in pole position to regain their Magners League crown.
O'Gara and co are guaranteed top spot in the standings and a home semi-final and the veteran playmaker is delighted that they now have a chance to end the season on a high.
"Harlequins was a very poor day," said O'Gara, who was a Magners League winner in 2003 and 2009.
"Harlequins are obviously a good team and I am not taking away from them for one minute, but you would expect us firing on all cylinders to beat Harlequins. But expecting and doing are two different things, and we didn't do it.
"We struggled in all areas, our execution was poor, and at this level small margins make a big difference. We didn't give ourselves a chance. "
"But the great thing about sport, and rugby, and the Munster team, is you get another opportunity."
The first stage of that opportunity comes against Connacht this Friday, when Munster return to Thomond looking to immediately exorcise their European demons.
Next up will be a semi-final at the same stadium against either Leinster, Ulster, Ospreys, Blues or Scarlets, while the Magners League Grand Final will also take place in Limerick should Munster make it through.
And although Saturday's defeat has undoubtedly dented Munster's pride, O'Gara believes that positives can still come from that particular reverse if lessons are learnt by a squad that has intergrated plenty of youngsters so far this term.
"There's an awful lot of the senior players that were young fellas once upon a time and they've had bad days before and if the right lessons were taken out of last weekend by the younger players it will accelerate their development hugely," added O'Gara, who was also quick to point out that no blame should be placed upon coaches Tony McGahan, Laurie Fisher and Jason Holland.
"But we do need fellas coming in and not looking just to get on the team, but coming in and trying to win European Cups. I think the ambition is huge and that's something the team needs.
"Tony, Laurie (Fisher) and Dutchy (Jason Holland) are not on the pitch. It's easy to blame them but the players were poor the last day.
"So let's take it on the chin, put your hand up; we played a bad game and they didn't coach us to play like that."
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