Winning solves Cullen problems
Rotation policy works for Leinster
There was scathing criticism of Leo Cullen last Christmas when the Leinster head coach made ten changes from Northampton Saints in The Champions Cup to Munster in the then PRO12 League.
It was seen as a sign of disrespect towards the interprovincial rivalry that has done most to put rugby where it is in the Irish sporting lexicon.
The stone throwers were out in droves when Leinster fell 29-17 at Thomond Park before 26,200 spectators.
This was around about the time the demise of the Irish in Europe was being viewed as inevitable.
This St Stephen's Day, the same coach made 12 changes, two more than last year, and there wasn't a peep of outrage at the devaluation of the biggest derby on the island.
What would have happened had Leinster not got out to the point-a-minute start or folded under the second-half pressure exerted by Munster on Tuesday?
The nay-sayers would have been out with the pitchforks forecasting the death of a once great tradition, despite the record-breaking 26,267 crowd in Limerick.
Once again, this has shown how winning is the best argument any coach can make in defence of his decisions.
The true difference is in the depth Leinster is building, even over the last 12 months.
This stretches from the signings of James Lowe and Scott Fardy to the superstar status occupied by Tadhg Furlong.
There is the rejuvenation of Cian Healy, the ongoing emergence of the likes of Ross Byrne, Rory O'Loughlin, James Tracy and Dan Leavy and the AIL promotion of Barry Daly from UCD to the Ireland training camp in Carton House.
Layered underneath all of that is the arrival of James Ryan, Andrew Porter and Jordan Larmour.
When has Leinster ever had the X-Factor one-on-one skills of Joey Carbery (currently out injured), Garry Ringrose, Lowe and Larmour?
All Cullen and Stuart Lancaster have to do is to figure out how best to use them within a system that must incorporate the pianists and the piano lifters. Not even Brian O'Driscoll could conjure up the magical sweep of 70 metres eaten up by Larmour at Thomond Park.
It followed on from his explosion of energy against Ulster in the Kingspan Stadium.
There, the St Andrew's College graduate left Iain Henderson grasping for thin air and Aaron Cairns in a similarly humiliating position for what was the purest try of the season before Tuesday.
This is not, for one moment, to suggest the 20-year-old is - or ever will be - mentioned in the same breathe as O'Driscoll when all will be said and done. What all of this does speak to is the different level of athlete coming out of the Leinster Academy.
Just before the beginning of last season, Carbery was fast-tracked onto a senior contract.
By the end of last season, Ross Byrne, Max Deegan and Porter had made the step up in a pre-emptive move by the coaches.
Perhaps, the single most impressive example of the deepening in the pool of talent is at number eight.
As Jamie Heaslip battles for one last chance at a comeback, Jack Conan, still just 25, has stepped up to the plate.
In behind, the Ireland U20s that reached the World Cup final in 2016 really is throwing up potential superstars.
Twenty-one-year-old Deegan is beginning to find his feet in the professional arena, through the British & Irish Cup, as another superior athlete with X-Factor attributes.
After that, Caelan Doris is smack bang in the middle of his preparations to be the Ireland U20s number eight for a second season.
Last week, Noel McNamara's band of brothers came up short in a trial match against Leinster Development at Donnybrook.
Nineteen-year-old Doris was the standout man and will be one for the future, sooner rather than later.
For all of Leinster's efficiency against Exeter in Europe, they did lack in the sort of one-on-one isolation danger Ringrose, when fully match sharp, Carbery, Lowe and Larmour bring to the game.
Then again, the various pieces of the puzzle that completes a champion club require the complementary gifts of graft, power and skill.
The secret to success is in blending all manner of men into one unit built for the purpose of winning.
Next up for Leinster is Monday's PRO14 clash with Connacht in the RDS (3.15).