Three-times a winning Heineken Cup captain with Leinster, he understands that fast starts can be absorbed into quagmires and that sluggish openings can be shrugged off with a belated generation of momentum through the pool stages.
So it was that the Leinster head coach could pitch up in the main stand in Glasgow after this most impressive of wins on Saturday wearing a distinctly impassive face and playing down the benefits of two opening Pool 3 games that have generated two wins and a maximum of ten points.
“We still have a long way to go,” he deadpanned. “There can still be a lot of twists and turns in this pool. What my experience will tell me is not to get too excited by the first two rounds. This group has a lot of ability but some of them are still young and some of them are trying to build up that level of experience. There are a lot of games to take place before we play our next Champions Cup game and that will be against a very difficult team in Exeter.”
This is supposed to be the detested ‘Group of Death’ and it makes the businesslike manner of Leinster’s opening engagements all the more notable.
Glasgow’s initial loss to Exeter in Sandy Park left them cornered and dangerous here and they stretched Leinster time and again with a trademark expansive game that prioritises speed and skills from all hands on deck.
Yet Exeter had beaten them with a more muscular approach and, though the Warriors coaches and players spoke of taking heed and dialling up the physicality, they offered the same challenge here and suffered the same consequences.
Leinster were more physical and more direct. Their setpieces were solid and they played the squally and wet conditions perfectly, especially in the first-half when facing the wind and the pre-game downpour had left the 4G pitch at its greasiest.
“We would have spent a good bit of time, particularly with the forwards, in looking at what Exeter did,” said Cullen. “It was pleasing.” Talk of ‘work-ons’ wasn’t far behind, but are they ever?
When Cullen and his cohorts study the video they will pick up on the flurry of individual errors that undermined the collective effort, most obviously the nineteen missed tackles that were added to the 33 registered the week before against Montpellier at the RDS.
The bigger picture, though, is harder to blemish. Cullen spoke on Friday about the experience injected into the team with the return of Jonathan Sexton from injury - and others - and the out-half was a composed and classy hand on the tiller throughout the afternoon.
Cian Healy had Leinster’s first converted try to bring the visitors level at ten apiece when Sexton directed a very kickable penalty to touch on the stroke of half-time and the end result was another five-pointer to Healy. It was the decision that wrestled the game to Leinster’s way of thinking. “Two of the big leadership calls he had was going to the corner midway through the half and the penalty on the ten-metre line just on half-time when in the past you could kick the ball off and the half was up or go for a crack at goal.”
Sexton would score the third try shortly after the interval with Noel Reid adding the fourth near the finish to ward off the challenge of a Warriors side that had claimed a sublime touchdown in each half through the returning Stuart Hogg and Tommy Seymour.
Leinster though look so much more prepared for the long haul. Even with Nacewa, Sean O’Brien and Garry Ringrose missing. Early days yet, as Cullen would say, but expect them to be there or thereabouts come the late spring in this evidence.
S Hogg; T Seymour, S Johnson, P Horne, L Sarto; F Russell, A Price; J Bhatti, G Turner, Z Ferguson; T Swinson, J Gray; R Wilson, C Gibbons, A Ashe.
R Harley for Wilson (10-23 and 26); S Cummings for Swinson (26-33) and for Ashe (62); A Allan for Bhatti and L Jones for Sarto (both 61); P MacArthur for Turner and H Pyrgos for Price (both 65); N Grigg for Johnson (68); S Johnson for Horne and G Turner for Gibbins (both 75); D Rae for Fagerson (78).
J Carbery; F McFadden, R Henshaw, N Reid, B Daly; J Sexton, L McGrath; C Healy, S Cronin, T Furlong; D Toner, S Fardy; R Ruddock, J van der Flier, J Conan.
D Kearney for Daly (42); J McGrath for Healy, J Tracy for Cronin and D Leavy for van der Flier (all 50): J Ryan for Frady (55); J Gibson-Park for L McGrath (62); M Bent for Furlong and R Byrne for Sexton (both 68);
J Garces (France).