McCarthy's performances have proven that he has what it takes at this level
You're damned if you do, and you're damned if you don't.
When playing these type of games, like the Kings, the focus is more on what scores you concede rather than what scores you rack up.
The manner and consistency in which Leinster performed will stand them well in the difficult weeks ahead but the main priority over the next block of games is the attrition rate from their own games and the Six Nations.
Without being controversial, there is no doubt that Joe Schmidt's recent game-plans with Ireland have been successful but highly attritional.
There is no doubt that these young players are ready for European selection if needed but the Leinster management will be still sweating on the overall availability of the players come March 18.
In Irish rugby today the only part of the game blocking the potential success of the provinces or international side is player availability.
Luke McGrath's absence from both the Six Nations and Leinster makes it unlikely he will be around for the Saracens game.
There has been much talk on the prospect of bringing in Jamison Gibson-Park and either James Lowe or Scott Fardy missing out.
I think Gibson-Park brings a lot to Leinster, particularly off the bench but for this match I think he might have to do what he's on these shores for, which is take one for the team.
If McGrath manages to be available I think it's an ideal opportunity to try out Nick McCarthy.
Last weekend McCarthy was very close to being the man of the match and although the opposition were not up to much, he has all the talent needed to perform at this level.
He has an ability to pass off both sides and he keeps the opposition defence honest by sniping around rucks. His box-kicks aren't bad either which seems so important for scrum-halves in Ireland these days.
These decisions will be crucial for the management, and the ability to think with forward progression instead of defaulting to their best XV from two years ago .
What is also interesting and yet frustrating is Garry Ringrose's return. He is clearly needed for both the Irish and Leinster team and his outing last week was enough for him to be in consideration for Ireland's last two games.
Ringrose's performances in the play-offs last season were outstanding and Leinster will need the same again for this season.
Handing him up to the Irish squad will not be easy for the management but in his case he does need game time at the highest level possible.
It is clear these days at Leinster's HQ that individual and not group player management will be vital in the coming years.
Finally, the news of Jamie Heaslip retiring is particularly poignant for me. I watched Jamie develop from the start of his career in Trinity College into a world class No 8.
In my generation of back-rowers we all had positive and negative attributes which led to a constant turnover in selection as we tried to improve ourselves.
But as I was constantly reminded by friends months into my retirement, Jamie had it all. This was and still is true, it will be a long time before we see a No 8 with such a grip on the Leinster, Ireland and Lions jerseys.
It was a pleasure to watch his professional attitude, his determination and success throughout the seasons.
These characteristics will no doubt be replicated in the big bad world outside of professional sport with equal success.
As Leo Cullen mentioned during the week he will be missed around the place and Leo personally requested his family continue their personal support for the squad.
As a brilliant career comes to a close, it's important to remember what's really important about the game and life outside sport.