The man behind the glass had the glare of one always haunted by the last thing he saw.
No matter the three wins over South Africa, Fiji and Argentina, Joe Schmidt was frustrated by Ireland's failure to show as much in the finish as they did in the beginning.
The Pumas, who started weakly, finished strongly for three tries in the last 25 minutes, two in the final ten minutes.
That leaves the sort of after-taste that takes time to fade from the palate of a rugby connoisseur like Schmidt.
Even in defeat, those aggravating Argies left their mark on Ireland.
"I know it is a little bit paradoxical to say I am delighted with the Guinness series and frustrated by a few things we didn't get right," he said.
"I know it is always a little bit like that when you try and strive to be better every time and, when there are bits that aren't quite right, you get frustrated.
"It was a little bit glum in the coach's box at the finish just because we conceded that try at the end."
That was to boil three test matches down into one post-match moment in time.
In fairness, Schmidt did not dwell too long on the negative.
There was Tadhg Furlong's growth as "a really strong character" on the back of the tight-head leading the tackle count (17).
Some of them carried all the authority of a Communist dictator.
The rehabilitation of the "incredibly dynamic" Cian Healy, the "further responsibility" taken by Iain Henderson in calling the lineout and the "unbelievably effective" CJ Stander all came in for mention.
In behind, Schmidt was taken with the impact of more than just his half-back generals Conor Murray and Jonathan Sexton.
"We have some incredibly hard-working and talented players," he said.
"You know probably, not the surprise package, but the real satisfaction for me was probably Chris Farrell's performance. I thought he was super."
New cap Adam Byrne did not look out of place, especially when having t o play out of position.
"For Adam, to have to go into centre was a big ask," he noted.
"I thought he defended really well there. He was more decisive and, maybe, it is slightly easier because you are a little more connected at centre.
"And Bundee (Aki) did a great job keeping him connected and guiding him along."
The gamble of going with just five caps for those numbered 11-to-15 paid a handsome dividend that will be fully recouped in time.
"Having looked at those guys, when you have Robbie Henshaw, Keith Earls and Garry Ringrose to come back in the midfield, it is a nice play to be.
"I just hope they are all available and make the decisions for the coaching staff as tough as possible in two months' time."
The door is not yet closed on those outside this November window.
There is time enough for a surge in form or the rapid rise of a newcomer to gate-crash 2019.
"I wouldn't discard anyone at this stage," he said.
"While you say it's two years away from the World Cup, I suppose my riposte would be that it's two months away from the Six Nations."
Schmidt turned his thoughts to Ireland's annual bread-and-butter to the exclusion of the "Johnny Come Lately" profile of the World Cup.
"I love the competition. You have fantastic crowds. Everything is a sell-out. You have atmosphere.
"I don't know, maybe 2013 and that New Zealand game, was probably even surpassed by that last few minutes against England last year.
"It has something that's a huge allure and we want to try and measure up."
First and foremost, France will be a huge block on the road to Six Nations glory on February 3rd.
"It has been in the back of my mind because we know how tough that's going to be," said the coach.