It must be the most difficult task of a physically non-taxing nature in football. How to learn from the master that is Stephen Cluxton while clinging to the belief that, some day, your championship chance will come.
Except it never does.
Over the last fortnight, Evan Comerford has become the fifth Cluxton 'deputy' to start an Allianz Football League match, joining Bryan Murphy, Paul Copeland, Shane Supple and Seán Currie. A sixth, John Leonard, never even got that spring chance.
Moreover, Murphy remains the only one to have tasted summer action - as an enforced sub against Armagh in 2003 after Cluxton's straight red card and then as starter for their '04 Leinster opener against Westmeath while Dublin's No 1 served out a one-match ban.
Cluxton made his summer bow back in 2001 but since he firmly established his starting credentials in '02, he has started every single league or championship final involving Dublin.
That's a staggering 25 - five All-Irelands, 13 Leinsters, six Division 1 deciders and a Division 2 final in 2008. Dublin have won 22 of them.
Leaving aside the fact that he's team captain and universally accepted as the greatest goalkeeper in history, this success rate helps to explain why Cluxton is virtually sure to start Sunday's NFL showpiece against Galway. Even though, or maybe because, he hasn't appeared in either of Dublin's last two outings.
"At the minute it's hard to see anyone ever replacing Stephen Cluxton," admits Barney Rock, "but then people said that about John O'Leary. There's always somebody coming along the line and hopefully, going forward for Evan, he'll get his opportunity."
Rock is well placed to assess his credentials. Not alone do they share the same club, but 'Dad of Dean' is now a Ballymun Kickhams senior selector under new boss Brendan Hackett.
The talented Comerford won two All-Ireland medals last season - one as a starter for the U21s when giving a stellar kickout display in the final against Galway, the other as senior understudy. After serving as back-up through 19 consecutive league and SFC fixtures stretching back to early 2017, he made his belated debut away to Galway last Sunday week.
A week later, with Comerford again deputising, they lost at the death to Monaghan. Two games and no victory; no wonder some sceptics were blaming Dublin's mini-blip on the absence of you-know-who. But Rock, a league ever-present this year, counters that Comerford is a "very good goalkeeper" who has held his own both in Salthill and Croke Park.
He reckons the only kickout faux-pas came in Galway when a delay caused by lack of outfield movement led to a hop-ball. His estimate that only one kickout was misplaced over both days might be slightly generous.
However, last Sunday's second half was notable for a stunning sequence of four consecutive long restarts - to Brian Howard, Michael Darragh Macauley, Colm Basquel and Macauley again - all delivered with Cluxtonesque precision.
"He didn't concede a goal (in Galway) and there wasn't too much he could have done for the two goals the last day," Rock points out.
"The first was put right into the corner and the second one ... when the two boys fell he came out to close the angle, and Jack McCarron did very, very well to lob it over his head."
Overall, Cluxton has now started 101 league games for Dublin, winning 60, drawing 12 and losing 29. His success rate over the last four leagues is almost off the charts - 20 wins, four draws and just one defeat. In the same 2015-18 period, Dublin have won four, drawn one and lost three of the eight league games in which he didn't feature.
Given it's a national final, Rock "presumes" Jim Gavin will go with Cluxton on Sunday. But Comerford has dealt with this scenario in the past: "Evan would have been there with Ballymun, when Seán Currie was the goalkeeper, and he would have been watching Seán who would have been learning from Stephen Cluxton."
It's all about learning.
And, for now at least, biding his time.