It was 41 minutes of chaos and within that time-frame Ulster had abjectly succumbed to all the pre-match hype suggesting that they hadn't a prayer of closing out the old year with anything other than a typical defeat at the RDS.
When winger Rory O'Loughlin had touched down for his second and Leinster's third try of the day, a mere one minute into the second half, Ulster had coughed up 22 unanswered points in a defensive horror show.
Leinster's first two tries, the second from scrum-half Luke McGrath, were so easily achieved that it actually looked as if the hosts were working their way through an unopposed training routine.
That Ulster actually managed to not concede again, while the home side failed to rack up what had looked a cast-iron certainty of a bonus point victory, proved to be a rather curious, and highly unexpected, outcome though Leinster's profligacy, Jack McGrath's yellow card, and their spiralling penalty count in the second half also contributed to this situation.
Yes, but no-one was deluded enough to even attempt camouflaging what had occurred or seek refuge behind the fact that Ulster, even with a malfunctioning lineout and Josh van der Flier doing damage at the breakdown, actually won the second half 7-5 when it was their turn to have the strong wind in their faces.
And certainly only managing to work Charles Piutau over the line in the 76th minute via Ruan Pienaar's inside pass - the South African then converted - had to be set against Ulster failing to shunt the scoreboard off zero earlier in the second half when Jack McGrath was sin-binned.
There were so many malfunctions in that opening half - Tommy Bowe's (right) dropped ball, when all he had to do was run in for a much-needed score, was horrible to witness - that you wondered what mental state Ulster were in when they took the pitch at a venue which has brought them so much pain.
Much had been made of the need to start well and the sight of Paul Marshall overcooking a touch-finder and Pienaar missing a long-range but wind-assisted early penalty certainly didn't bode well. But when Ross Byrne hit O'Loughlin with a pass, the next few seconds were as bad as Ulster have produced in this, already, inconsistent season.
The young winger steamed through a gap between Stuart McCloskey and Pienaar - the South African never looked comfortable while at out-half - and then skinned Andrew Trimble before rounding Marshall and running on to dot the ball down.
Isa Nacewa then judged the conditions perfectly to steer the conversion home.
Pienaar couldn't get Ulster off the mark shortly afterwards with a miss from the tee although it was closer to the sticks than his first effort had been.
That was costly and then it just got worse. Nacewa had pushed things to 10-0 by landing a great penalty on 17 minutes when Leinster missed the restart and Bowe was there to catch, and then simply drop, the ball as he prepared to hit the unprotected corner.
If Ulster already hadn't realised that this wouldn't be their day then they certainly did a few minutes later when Trimble charged down an O'Loughlin clearance, in Leinster's 22, only for the ball to tamely bounce back into the blue-shirted player's hands allowing him to effect a more impressive exit.
The net result of that moment saw Sean O'Brien surging towards the Ulster line. The Ireland flanker, though, chose not to use O'Loughlin and Garry Ringrose's support lines and opted, instead, to run through Piutau who stood his ground with the shuddering impact forcing the knock-on.
But Luke McGrath's try, two minutes after the half-hour, took the bad look off that wasted chance for Leinster and dragged the visitors' down to a new low.
This time it was a lineout and Leinster - noticing there was space in behind Ulster -opted to throw it short to prop Jack McGrath at the front.
He turned and fed inside to namesake Luke who tore through a gap in the forwards and cantered home while opposite number Marshall was absent as he had been standing out nearer the touchline.
Nacewa made it 17-0 at half-time and when the sides came back O'Loughlin had his second try after just a minute's play when Byrne's grubber through bounced up for him.
With the game over, Ulster finally managed to play a bit - though they still turned over too much ball - and they appeared to get a break when Jack McGrath was binned on 57 minutes for killing the ball near his line, though the sight of Darren Cave cutting back in, with space outside, was less than reassuring just before Leinster went down to 14.
Neither was seeing Bowe fail to hold a Piutau off-load on the other side of the field but as Ulster tried to make their extra man count, Piutau's pirouetting run resulted only in Clive Ross being emptied by Ringrose and Cave's hurried pass to Kieran Treadwell going to ground.
So with no points scored during Jack McGrath's time away, Ulster's misery looked complete only for Pienaar - now safely installed at scrum-half - to combine with Piutau and then add the two points just four minutes before the final whistle.
That allowed the cowed visitors, who had earlier lost Rob Herring, Roger Wilson and Rodney Ah You to injury, to make their escape.
Leinster: I Nacewa; A Byrne (A Porter 57; J Loughman 65), G Ringrose, N Reid, R O'Loughlin (Z Kirchner 65); R Byrne (T Daly 73), L McGrath (J Gibson-Park 60); J McGrath, S Cronin (R Strauss 60), M Bent (J Loughman 66), D Toner, H Triggs (M Kearney 66), S O'Brien (J Conan 69), J Heaslip, J van der Flier.
Ulster: C Piutau; A Trimble (L Ludik 59), D Cave, S McCloskey, T Bowe (J Stockdale 65); R Pienaar, P Marshall (B Herron 73); A Warwick (C Black 62), R Herring (capt) (J Andrew 28), R Ah You (J Simpson 48), K Treadwell, F van der Merwe (P Browne 73), C Ross, R Wilson (C Henry 54), S Reidy.
Referee: J Lacey (IRFU)