This was one of those very frustrating Leinster performances where they decide to tie one hand behind their back rather than put on the 60 points which Northampton deserved.
The blue side eventually prevailed with a really sloppy performance still way too good for anything that Northampton could conjure up. Amazingly, the English Premiership side were still in the hunt deep into the second half in a match where Vaudeville mistakes at every turn could have made it closer than it needed to be.
Leinster committed in excess of 20 handling errors in admittedly difficult conditions and they let their enthusiastic but outmatched opponents hang around with the persistency of consistency of effort.
It's the only thing you can say about Northampton. Unlike other matches in the recent past against Leinster, they kept the white flag well hidden in the gear bag and they were given encouragement and no little nourishment from a rash of Leinster mistakes throughout a shoddy 80 minutes.
The format of the competition is different this year and an immediate return match against the Saints back in Franklin Gardens would have been a tricky assignment. Northampton travelled with a far stronger complement than they had advertised. I don't think it would have made any difference if Dan Biggar and Courtney Lawes were part of their starting side. I think it would have meant that Leinster may not have played with what amounted to a sleep-induced torpor.
The likelihood is that in January Leinster will have Tadhg Furlong, Dan Leavy, Caelan Doris, Luke McGrath, Johnny Sexton and James Lowe in their starting side. You may say what you wish about Grumpy but he does not countenance that sort of performance when he is on the pitch.
I wonder whether Leinster are being asked/told to play Jamison Gibson-Park from the start. It has been obvious for the last three years that McGrath is the superior player. I think Leo Cullen and Stuart Lancaster think this too.
It is amazing that one poor performance behind a badly struggling pack in the Heineken Cup quarter-final against Saracens can undo a serious body of good work. The competition for the starting spot is so much more than tempo over structure. McGrath is so much the better player that it is not even a competition. Even John Cooney playing badly is a better proposition and I still cannot believe that the Kiwi has been capped by Ireland.
Gibson-Park did many things well yesterday, but the deficiencies in his game were there to see and if you wanted to point a finger at why Northampton were still in this game, you wouldn't have had to look too far.
You may, if you have been watching Leinster play since the start of this season, have detected something in their options close to the line, particularly when they have been given a penalty inside five metres. Some observers think it is the equivalent of E=MC squared.
A bizarre moment occurred in the 15th minute of this game. Northampton were awarded a free-kick on their five-metre line. The scrum collapsed and then Leinster were awarded a free-kick.
Leinster took the scrum and, like they have been doing, decided to tap and go five metres from the line. Irrespective of what defence you are playing against, the likelihood is that when you tap and go that close to the line you will be within sniffing distance of a try.
Normally if you get a full penalty and you go for the lineout maul you will be pushed off the five-metre line by at least three metres if the opposition pack you're facing is even half-decent.
But, with all Leinster's inconsistent throwers, you are never absolutely certain of winning the ball. A tap and go is the percentage play and has been for 20 years and Leinster (a couple of months before anybody else) finally discovered that.
Rónan Kelleher got to within a metre of the line and sure enough on the next phase Cian Healy got over. Why bother with all the palaver of the committee meeting, the Hail Mary of actually winning the ball and then a Leinster pack who have lost the art of mauling.
We know why Leinster shouldn't do the lineout mauls anymore. As part of their cunning plan to keep Northampton in the game when they should have really closed it out, in the 58th minute they passed up the opportunity to tap and go on a full penalty five metres from the line to go for a lineout maul which we all knew wasn't going to work.
Leinster had their committee meeting. James Tracy was throwing the ball in and the Leinster lineout from the five-metre line back was Peter Dooley, Rhys Ruddock, Michael Bent, James Ryan, Josh Murphy. Ryan Baird and Josh van der Flier were placed at the back.
There was going to be movement up and down the line and this was going to be a timing play. Quite how a professional side can get it so badly wrong is beyond me. From the go Bent moved from three to the No 5 position - did a feint to lift Baird which was badly executed as neither party had enough time to pretend to get Baird into the air.
Then Bent turned around completely out of time to get their real target into the air. The lift was nearly two seconds too late and the ball missed Murphy as it was two metres too high when it went by the No 5 slot in the lineout. The lift comically came hours later but still, even at the height of Murphy's jump, would have been a metre too high.
The ball flew to the very back of the lineout but it was also crooked on the Northampton side and that is why Northampton's George Furbank picked it up more easily than he should have.
Northampton weren't buying any of this Leinster razzmatazz and had kept their troops on the ground and not in the air. Even from a distance it was obvious that Northampton weren't going to launch. You could have thrown it flat directly to Ruddock at the front and that would have been that.
Why do Leinster do this? Why do they over-complicate things - particularly in the red zone? How could their timing be that badly off? Why don't they just keep things simple? Why bother going for the lineout in the first place? Why not tap and go? Wait a minute, I think I've realised why Leinster tap and go in the first place.
Rhys Ruddock was calling the shots - no Christmas pud for him or maybe make him eat the whole thing as punishment.
Meanwhile, in the Auvergne, there was a renaissance. A truly phenomenal performance by Munster, led ostensibly by a new brigade who had to learn afresh how to win away in France, something that has eluded Munster in the last five years.
I am sure the post-mortem in Clermont will be a finger-pointing exercise focussing on how they could only score three points to add to their 28-point first-half total. There was enough leadership and quality in the French side and yet they were rudderless and lacking the sort of cohesion they enjoyed in the first 20 minutes.
The truth is Munster inflicted themselves on Clermont and played a pressure game in the French 22. Clermont just couldn't seem to get out, even when there was an opportunity for a clear exit.
The heads began to drop in French ranks as Munster more and more realised that the victory was there for the taking. This win may go a long way towards saving the head coach's neck. It was as timely as it was convincing and the only regret we have now is that the two super-power Irish sides will put out a seconds/thirds side on St Stephen's Day.
This was one of Munster's greatest victories.