Cardiff display showed Cullen's men have workrate and passion to land Pro12 title
Sometimes the work and preparation put in at training leading up to a game shows from the off come matchday, and last Saturday's victory in Cardiff was one such occasion.
It is clear back in Leinster HQ that the youngsters see an opportunity to dominate proceedings at this time, and a wind- and rain-sodden Cardiff was not going to get in the way of the opportunity for points, like this weekend against Zebre also provides.
Talk can be cheap in professional sport, but in Jack Conan's interview after the game - he was a deserving man of the match winner - he spoke about the determination during the week which led to their belief in the game. When you're able to walk the walk too, it makes the miserable weather conditions insignificant.
Sometimes you learn more about a team's mental state from the way they defend than the way they attack, and currently Leinster have a belief and workrate not regularly seen this season.
With Kurt McQuilkin only half a season embedded back in Leinster, his stamp on the game was highlighted by a dogged, structured defence that Cardiff in the comfort of home could not penetrate.
If the Leinster management were content on Saturday evening, so too were the Irish management. From the start, Cian Healy obliterated the Cardiff scrum. Unfortunately for him, his abundance of power was over-used at a crucial time that resulted in a Cardiff scrum from an attacking Leinster position.
With Cian Healy back playing well and the current form of Jack McGrath, the loosehead position has never been so strong for both province and country. This gives the future of both squads an attacking scrum platform, which has always been an asset to any team - no matter what generation.
But in the end, it was the workrate of their pack that won Leinster the game. No disrespect to the backline, where there were great individual performances - particularly captain Isa Nacewa and Ian Madigan - but with the lineout a lottery, the game was always going to be won at scrum time and on the ground.
Last week's away game proved that sometimes passion and workrate are the best attributes for success. And in the final period of the season ahead of Leinster, those traits will be needed the most.
I think their determination to overcome the elements and distractions and win away to Cardiff is an indication that Leinster have the ability to win this year's Pro12. The importance of winning this league will give confidence to all involved in Leinster, and bridge this period of transition with the exciting times ahead.
Maximum points is a must this Sunday away to Zebre and for a team that battled in the trenches of Cardiff last weekend, it will be difficult mental challenge to have the same motivation against the league minnows in Italy.
Next week's game against Ospreys will be a chance to prove to the home crowd and themselves that Leinster can finish well this season.
The rehabilitation of Healy and Mike Ross for the national team is a thankless task for Leinster. Although, the loss of Mike McCarthy and Sean O'Brien from Ireland might eventually be Leinster's gain.
Through a season that has had its ups and downs, the player production line has remained steady with young players taking their opportunities when given them, while their pride in the jersey shines through when they faced difficult fixtures in a wayward season.
Hayden Triggs, Ben Te'o and particularly Nacewa, have done what they were supposed to do, by steadying the ship when Leinster have been down their frontliners.
Nacewa's leadership has been evident throughout and a lesson to other provinces and the national side.
Come April, Leinster should be in pole position in this league, so if it ain't broke, don't fix it.