O'Brien's stirring performance further proof of strength-in-depth in Ireland's back row
Depth is not a word over-associated with Irish rugby. With a playing population far below the likes of England, France, New Zealand, Wales and South Africa, Ireland selections over the years have, by necessity, tended to veer towards an 'old reliable' policy.
However, in the back-row, Ireland coach Declan Kidney and his management team have a plethora of options heading into World Cup year and Sean O'Brien is top of the pile. The 'old reliable' in Ireland's breakaway unit is Munster's David Wallace, whose impressive December displays emphasised the welcome headache for Kidney. But, with Wallace rested yesterday for Munster's Magners League trip to Galway under the Player Welfare Programme, Leinster's assignment at Ravenhill against Ulster was the perfect opportunity for O'Brien to lay down another marker.
Following two tries in the opening 14 minutes and a man-of-the-match performance, in attack and defence, characterised by physical intensity and overall dynamism, it is safe to say the Tullow man did just that. And depth, in a different way, was key.
The pass may have been forward for O'Brien's first score, but the line he ran off the shoulder of scrum-half Isaac Boss and the momentum he had built up by the time he received possession were sublime.
Running from deep is something that used to be drilled into rugby players from an early age but in recent years the sight of players taking possession in static positions has been far more commonplace.
After six minutes, O'Brien had built up a head of steam when he took the pop from Boss, allowing him to sweep contemptuously past BJ Botha before handing off another Springbok, Ruan Pienaar, on his way to the line.
Eight minutes later, O'Brien served up a repeat, tearing on to Boss' pass for another touchdown under the posts, this time untouched.
There were plenty of cameo moments to savour, including yet another perfectly timed run from deep setting up a powerful surge and sweet off-load to Brian O'Driscoll on 53 minutes, a move which ended up with a try for Shane Horgan on the wide right.
Another charge up the right touchline seven minutes later saw O'Brien intelligently assess his lack of support and slow down into the tackle.
The delay allowed him the time to hit Boss with an off-load from the ground and, suddenly, the ball had been moved from Leinster's 22 to the UIster half.
The Ireland Grand Slam back-row of Stephen Ferris, Wallace and Jamie Heaslip is seemingly set in stone but, if O'Brien maintains this run of form, he will demand inclusion in one of the three positions.
Lack of height has been a selection issue in the past, and O'Brien will never be the line-out option for Ireland that Juan Smith is for South Africa or Jerome Kaino for New Zealand, but that situation can be managed by Kidney and his forwards guru Gert Smal.
Aside from O'Brien, the other cause celebre in Irish rugby looking ahead to the Six Nations is Mike Ross but the Leinster tight-head, so impressive in the scrum against all-comers this season, had a proper battle against Ulster's young loose-head Paddy McAllister and his experienced replacement Bryan Young.
The fact Ross had 6'10" Devin Toner behind him rather than Nathan Hines has to be factored into the equation -- the laws of physics decree that it is harder for Toner to get into the most effective driving position -- but the Cork man, although conceding a few penalties, won a few of his own and popped up around the park also.
Toner had a good outing in the second-row, making life easier at the line-out for rookie hooker Jason Harris-Wright, who caught the eye with a committed all-round showing, notably in defence.
If O'Brien was the star turn, former Ulster stalwart Boss was not far behind him. After Eoin Reddan's excellent showing last weekend against Clermont, scrum-half is another position where Leinster are well served.
And we are back to depth, again. Dominic Ryan, Rhys Ruddock, Fergus McFadden and Dave Kearney all had their moments alongside their older colleagues while Ulster, although deeply disappointing until the final quarter, and Kidney can take solace from the performances of McAllister and Nevin Spence as well as Willie Faloon and Paul Marshall off the bench. It was the contribution of their South African contingent that most frustrated and raised, yet again, the issue of overseas recruitment at the expense of home-grown talent.
At the moment, it seems to be a case of low return for high investment in Ulster. Faloon being forced to sit on the bench to accommodate under-performing Bokke appears preposterous.
Consider this question, how much is Ruan Pienaar being paid compared to Sean O'Brien and who is worth more to Irish rugby? If that's not too deep...