Illustrious company thats for sure - didn't realise that you rated him so highly! What happened to that Argentinian fellow?
I must confess that being an old git I was probably looking back a bit further than this - I wonder how many 18 year olds Ramsey, Revie or Greenwood picked?
Edit I have answered my own question - None!
16 players have been capped for England before their 19th Birthday 5 of those before 1905, then Duncan Edwards in the 50s, Owen in the 90s and all the others this century.
Jimmy Greaves won his first cap aged 19, but he had scored 59 goals in 84 first team starts at that point - So I conclude that it may have been harder to get a cap then that it is now!
Would now be an awkward moment to point out the Croatian player is Alen Halilovic, whose most notable achievement was managing to play for teams relegated from La Liga the Bundesliga in the same season?
While you cite Ramsey, Revie and Greenwood for not giving debuts to 18 year olds, that doesn't mean the rest of the world weren't, for example the following players made their debuts between the mid-50s and mid-80s
Wlodzimierz Lubanski (16, for Poland...what do you mean you're not surprised?)
Georgi Sokolov (16, for Bulgaria)
Sigurdur Jonsson (16, for Iceland)
Pele (17)
Diego Maradona (17)
Ferenc Puskas (17)
Harald Nielsen (17, for Denmark)
Jimmy Holmes (17, for Ireland)
Michael Degiorgio (17, because Malta count...right?)
Marco van Basten (18)
Michael Laudrup (18)
George Best (18)
Uwe Seeler (18)
Frank Rijkaard (18)
Giuseppe Bergomi (18)
There's no doubt plenty more in that time frame, but I can't be arsed to dredge up every last example because we'll be here all day, but that does demonstrate a pattern: some players were fast tracked into their international team between the ages of 16-18 as they were obviously standout prospects, some had good debut seasons so were quickly elevated to mixed results, and some because the national team was crammed with dross so you may as well get the next generation of dross in early.
The real difference between then and now is that it's far more likely for a player to change the nation they represent, for example in the 60s the Portuguese were able to stick Eusebio on a plane in Mozambique and chuck him on a pitch in Lisbon to guarantee he was a Portuguese international, but that's not the case these days as players can switch allegiances as demonstrated with the likes of Declan Rice, Jack Grealish, Wilfried Zaha, Victor Moses or Dom Dwyer to name but four that means that if an FA keeps a player waiting too long they can up and leave for another, or in the case of Rice and Grealish basically become plastic internationals (which hasn't exactly worked out for Grealish, has it?) while Dwyer was never going to play for England so a call from the USIEAIAIO was a no-brainer
