Edinburgh might talk of fighting on two fronts this season, but in their final RaboDirect PRO12 outing before the Heineken Cup begins they were desperately slow into their stride.

Had you been scoring it like a boxing match, you might have put them ahead in the final quarter, but in no significant period before that. As a last outing before they take on Saracens next weekend, it was a deeply worrying affair.

Critically, they made far too many basic errors on the ball, making it all too easy for Treviso to take their first victory in the capital. With a couple of gift-wrapped scores, the Italian side did nothing fancy, but they were efficient in possession and fierce in defence. Edinburgh's corresponding qualities were profligacy and porosity. The Scots simply didn't do enough to win.

At least the performance did establish John Yapp, who replaced Allan Jacobsen early in the second half, as Edinburgh's best loosehead prop, although Jacobsen might argue that the heavy knock he took just before the interval had an effect on his performance.

Dave Denton, making his first appearance since being injured on the opening weekend of the season, made a quiet return, although he did play a critical part in Edinburgh's first try. Other than that, Netani Talei impressed when he appeared late in the game, although the momentum was with Edinburgh by that point.

For the second time this season, Edinburgh were obliged to face an Italian team with an Italian referee in charge. As understandable as it might be for league organisers to want to establish the autonomy of match officials, it would have strengthened their case if Matteo Liperini's own performance was above reproach. As it was, the Italian mystified the Edinburgh players and infuriated the Murrayfield crowd with a sequence of bewildering decisions, the vast majority of them going against the home side.

The most shocking of all was when he yellow-carded Willem Nel for driving up in a scrum in the 24th minute, when it was patently obvious that it was Michele Rizzo, the Treviso loosehead, who had been first to pop out of the set-piece. The consequences of that error became clear five minutes later when Treviso won another scrum deep in Edinburgh territory, drove their opponents backwards and walked away with a penalty try.

"We were confused by the refereeing of the scrum," said Edinburgh coach Michael Bradley, whose side have now lost three games on the trot. "It had a major impact on the game. Our scrum has been excellent all season but we conceded four penalties there in the first few minutes.

"But we had enough chance to win the game in the second half. We managed the referee better. Treviso are a good side, a tough side, but we're very disappointed."

In fairness,, Edinburgh deserved a bit of punishment on the scoreboard by that point, for even at full strength their early efforts had been distinctly unimpressive. They had coughed up possession far too easily, putting themselves on the back foot and allowing the hard-running (and substantially built) Treviso forwards to make significant inroads into their territory.

Edinburgh were clearly infuriated by Nel's sin-binning and the Treviso try, but at least they put their anger to good use. Four minutes after Alberto Di Bernardo had added his conversion to put Treviso 7–3 ahead – Laidlaw had clipped over a penalty in the fourth minute – Dave Denton powered away from a scrum near halfway, slipped the ball to Tim Visser, and the winger rounded two defenders before collecting his eighth try of the season.

Di Bernard's 38th-minute penalty brought parity, 10-10, which would have been a decent interval scoreline on the balance of play. Would have been, that is, had Edinburgh not suffered a calamitous episode in the final play of the half as they tried to build a move down the right flank. A loose pass saw the ball hit the deck, at which point Robert Barbieri, the Treviso No.8, hammered away with the thing, survived a despairing tackle attempt by Matt Scott and scored between the posts.

To lose one try to a howling error is unfortunate, but losing two can begin to look like carelessness. Yet Edinburgh did just that when, in the 55th minute, replacement scrum-half Richie Rees's attempt to clear up behind a lineout was charged down by Barbieri, and the forward pounced to collect his second score. Di Bernardo had already claimed a penalty early in the second half, and his conversion gave Treviso a 27-10 lead.

Edinburgh cut the gap almost immediately, churning the restart ball through a couple of phases before unleashing Lee Jones down the touchline. It was just the fillip Edinburgh needed. So, too, was the arrival of John Yapp, who took the place of Allan Jacobsen and immediately brought his bulk to bear in the scrum. A set-piece that had been creaking became a powerful attacking force. Almost inevitably, Treviso prop Alberto De Marchi was soon heading for the sin bin, but that dose of restorative justice had no immediate impact on the scoreline. The game was in its 78th minute before Dougie Fife, who had replaced Greig Tonks after 40 minutes, broke through for the third try, which Laidlaw converted. Edinburgh fought desperately for a winning score, but the effort ended when, after umpteen phases, Visser kicked too far ahead and Treviso mopped up.