Before the month-long break, the race for the top four was already tightly bunched - five points separating first to fifth - and the Ospreys could well slip down the order once the weekend's dust is settled.
New Zealander Jade Te Rure impressed for Edinburgh on debut, scoring a try, conversion and penalty, as Alan Solomons' side took away a 24-16 victory.
There was just one point in it heading into half time as Sam Davies struck three penalties but Grayson Hart and Tom Brown saw Edinburgh finish their night with a flourish, despite a late Dan Evans consolation.
And though Ospreys had 23 players unavailable due to a combination of internationals and duties, Tandy refused to make excuses for critical handling errors.
"We coughed up the ball far too many times," said Tandy. "There were too many basic errors, and the minute we got into opposition territory and got some field position, we spooned the ball and coughed it up. It's a bitterly disappointing night for us.
"I think we played some good stuff in the first half, had a couple of opportunities, and at this level when you come away from home you need to take those. You can't expect to win games when you stack up as many errors as we did tonight. It's as simple as that.
"Clearly the set piece is an area we've got to keep working on but tonight was about more than just that."
Nevertheless the Ospreys are still in a healthy position in their bid for a return to the GUINNESS PRO12 play-offs.
And while their schedule does not get any kinder, with a visit to Glasgow Warriors next week, Tandy insists he remains excited about the young talent being handed their chance.
"This is a tough block for us but it's something that we were pretty excited about coming into it. I think that makes this harder to take," he added.
"With the injuries we've got, and the international call-ups, it does ask more of our young kids, and on the whole we are pretty pleased with them. It's just we weren't good enough.
"It's going to be another tough encounter next week, and the reality is that if we play like this against Glasgow we'll find ourselves on the end of a pretty harsh scoreline."
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