O'Brien ready to deliver a big performance in crucial battle at the breakdown
If you were to put a positive spin on the last two games, Leinster have repaired their squad physically.
Flexible, courageous and varied selection has rested and rehabilitated individuals in the squad and given valuable game-time to a bunch of up-and-coming players. The result of all this is that the management have managed to increase their options when it comes to selecting their best 23 for Sunday's semi-final against Toulouse.
What is the underlying unspoken is that Leinster have copped some gut-wrenching performances and a loss along the way.
We can look back at last season's success and such losses were very much in the minority.
This season, those defeats have been more frequent and not helpful to the squad's mental preparation, considering most of the squad were tied up with Ireland prior to the recent block of Leinster games, where under-performing has become part of the norm.
If you look at the problem areas for Leinster against Toulouse, they are vast.
Toulouse historically have their loose and broken play threat engrained in their DNA and therefore can attack from anywhere.
Preparation Modern-day Toulouse have more structure to their game and apply more time in their preparation against the opposition.
International Rugby Newsletter
They have a solid scrum and lineout, which have stood them well so far this season and will be matched by equally strong set-pieces from Leinster.
Add this to their open-play culture and it is obvious where Leinster will need to halt the French side - the breakdown. If Leinster can shut down Toulouse in this area, they can win this game. If not, this brazen Toulouse side can push on and challenge for their fifth European title.
With Josh van der Flier and Dan Leavy injured, there is a big onus on Seán O'Brien. A lot has been written about O'Brien's form recently and as usual, people have short memories on what he has done for province and country.
Johnny Sexton has not played since the Wales defeat, while O'Brien has played every game. As a player, in your early 30s, the player welfare programme and sports science would suggest cherry-picking the games for maximum personal performance.
This works with the younger players but not the older ones. Rob Kearney refutes his detractors the more games he plays.
O'Brien's form is gradually returning to his best and you can be damn sure he will leave these isles with performances for us to remember him by, but the question is what works best for Sexton?
Sexton was rested before the England game in the Six Nations and by his own high standards has been poor ever since.
Like the O'Brien and Kearney, he is in his 30s and being laid up will not work for him and instead will lead to frustration from within his own high expectations.
If you add the captaincy into this, it's a big ask for the current World Player of the Year.
While it is great to have him available, there is strength off the bench if needed in Ross Byrne and this will give the management and team confidence in Sexton playing his way back into form.
The other selection conundrum comes with the foreign players. There is no doubting the need for James Lowe on the pitch due to the nature of his attacking game.
However, damage limitation will come into play with selection. The recent return of Devin Toner will mean the requirement of the in-form Scott Fardy either in the XV or on the bench.
The same goes for the recently injured Luke McGrath, who will need Jameson Gibson-Park as back-up. This is where Lowe may miss out.
In open play, Toulouse are the most dangerous. A genuine openside flanker would be able to manage this but you can be guaranteed with the experience of O'Brien, Jack Conan and Rhys Ruddock, they will get there using wise short cuts.
Decline With the recent decline in expectations in Irish rugby, players need to be selected on what they can do as opposed to what they cannot.
There are a lot of murmurs coming from the management that the squad can pull a big performance out of the bag when needed.
However, this is new territory for them. This time last year Leinster had robust momentum and confidence.
This gave them the ability to pull performances and wins even when the play was going against them as their belief in themselves was the foundation of all their performances in both competitions. This year Leinster are more vulnerable.
What will win this game is the wise old heads of the senior players. There is no doubt that Leinster are not as mentally tough as they should be at the moment but if they can grab control this game then they can dictate the pace and their own performance.
What will be most crucial also is the crowd participation. Leinster players will need to give the crowd hope and belief for the next six months and the crowd will need to scream out their frustration from the last six months.