Comment: Martin O'Neill can't afford to persevere with players who are not getting game-time with their clubs
When Ireland finally made the breakthrough into a finals of major football tournament for the first time 30 years ago next week, virtually every member of Jack Charlton's squad was playing regular top-flight football.
Liverpool, Manchester United, Arsenal, Everton and Celtic all provided players for Big Jack's squad which stunned England in Stuttgart's Neckarstadion on June 12, 1988 and created Irish football history thanks to Ray Houghton's early winning goal.
In contrast, the majority of Martin O'Neill's squad which blew World Cup qualification last November, and is now emerging from the embers of that damaging Danish defeat, have been fortunate to get a regular game in the Championship this season, never mind the Premier League.
In fact, take away Europa League qualifiers Burnley, where five Irishmen, including the injured Robbie Brady, are in Sean Dyche's squad, and the lack of Irish players in the English top flight is alarming.
It was down to just 25 registered players last season, although there will be three additions to that list next season after Matt Doherty, Anthony Pilkington and Cyrus Christie all gained promotion at Wolves, Cardiff City and Fulham respectively.
The list includes Declan Rice's West Ham team-mate Josh Cullen, a midfielder who returned from a loan spell with Bolton earlier in the season and was a regular on the bench under David Moyes.
There is Everton's Sam Byrne, Liverpool defender Conor Masterson, Manchester City midfielder Tyreke Wilson, Southampton pair Michael Obafemi and Aaron O'Driscoll, Watford's Tommy Hoban and Dara O'Shea, who was in the relegated West Bromwich Albion squad with James McClean.
Jayson Molumby, Aaron Connolly and Des Hutchinson were used in the League Cup by Brighton's Irish manager Chris Hughton in the last 12 months but they have yet to play in the Premier League.
The biggest concern for O'Neill is the number of Ireland players on the fringe of his squad because they are on the fringes of their clubs.
To cope with the additional demands of European football, and the challenges of Thursday/Sunday matches next season, Dyche is looking to strengthen his squad, rather than sell, which could be a mixed blessing for Ireland's ageing striker Jon Walters, who spent most of his debut season at Turf Moor in the treatment room.
O'Neill may feel Walters needs games to remain integral to Ireland but Dyche may disagree.
The first player to secure a summer move to a new club is the least helpful to the Ireland manager.
Before playing in his final international match for his country, John O'Shea agreed a deal with Championship club Reading.
O'Shea, who retired from Ireland duties after his 118th game for his country on Saturday, will sign a one-year deal with Reading where he will join Paul McShane, another former Sunderland, Manchester United and Ireland defender.
The Waterford man had been hoping to extend his career at Sunderland, despite successive relegations from the Premier League to League One under his captaincy.
However, the Wearside club's new manager Jack Ross and owner Stewart Donald have decided not to take up the option of an additional 12 months for O'Shea, who joined the Black Cats from Manchester United in a £6m deal seven years ago.
O'Neill is hoping that several players in his new-look squad will follow O'Shea's example and make a move during the summer.
Shamrock Rovers striker Graham Burke, who on Saturday became the first League of Ireland player to score for Ireland since Ray Treacy 40 years ago, has attracted interest from Nottingham Forest and Preston North End, who are likely to accept offers for Daryl Horgan.
Horgan, a lively 61st-minute replacement for Graham Burke, has had a frustrating season at Deepdale under Alex Neil and started only two Championship games for a team which finished just outside the play-offs.
O'Neill admitted the 25-year-old former Sligo Rovers and Cork City winger, who was signed from Dundalk by Simon Grayson two years ago, may need to move if he is to secure a regular slot in his squad.
Horgan's enthusiastic contribution to the last half-hour against the Americans will not have gone unnoticed by the posse of senior scouts from Premier League and Championship clubs who were at Saturday's match.
Other players will also have been on their radar. Harry Arter has been on the bench at Bournemouth since the turn of the year, David Meyler is leaving Hull City and West Brom's James McClean has been linked with a move to Stoke City after both sides were relegated from the Premier League.
In most cases, O'Neill and his coaching staff will simply want to see them start games regularly, even if that is in the Championship, or League One.
So when he picks up the team sheet at Aston Villa before a game, he might expect to see Scott Hogan starting and scoring, rather than watching from the bench, as he did for most of last season.
Enda Stevens, who made his Ireland debut against the Americans, started 45 games for Sheffield United last season but he is a rare case.
John Egan, Alan Judge, Chiedozie Ogbene (all Brentford), Callum O'Dowda (Bristol City), Eunan O'Kane, Conor Shaughnessy, Paudie O'Connor (Leeds), Shaun Williams and Aiden O'Brien (Millwall), Ryan Manning (QPR) and Keiren Westwood (Sheffield Wednesday) have all been in and out of their starting line-ups and started fewer than 30 league matches.
It is a situation which will not change before the Nations Cup kicks off in September in Cardiff but O'Neill will be hoping that things improve as the Euro 2020 qualifiers approach.
It's such a very different landscape to the one Charlton enjoyed all those years ago.