Van Gaal was hailed as a genius after bringing on Krul for regular goalkeeper Jasper Cillessen in Netherlands' penalty shootout victory over Costa Rica in the quarter-finals of the FIFA World Cup but did not repeat the move versus Argentina, having already used his three subs.
Cillessen has never saved a penalty in his professional career and failed to stop one in Sao Paulo, as Argentina won the shootout 4-2, after the game remained scoreless through 120 minutes.
At half-time, Van Gaal brought on Daryl Janmaat for Bruno Martins Indi, who had received a yellow card in the first half after struggling to defend Argentina captain Lionel Messi, while Netherlands' coach inserted Jordy Clasie after the hour mark for Nigel de Jong, who was coming back from injury.
In the first period of extra-time, Van Gaal used his final substitution in an attacking move, bringing on Klaas-Jan Huntelaar for Robin van Persie but the 62-year-old admitted afterwards he would have liked to bring on Krul for the shootout.
"If I could've substituted him [Cillessen] with Krul, then I would've done. I reached penalties with no more substitutions left," Van Gaal said at his post-match media conference.
Van Gaal attempted to deflect attention from his failure to save a sub for Krul by dismissing the shootout as "a matter of luck", while he also jokingly took credit for the two saves of Argentina goalkeeper Sergio Romero, who he coached at AZ Alkmaar.
"Of course penalties are a matter of luck too. And I taught Romero how to save penalties," he said.
Netherlands had received plenty of criticism both abroad and at home during the World Cup for abandoning their traditional 4-3-3 formation and playing defensively-focused, counter-attacking football.
But Van Gaal praised his team for a "marvellous tournament" and argued they had gone much further than anyone had expected.
"Holland played a marvellous tournament," the future Manchester United manager said.
"Nobody could've imagined we'd come this far.
"Argentina are a world class side with world class players and I'd like to point out we didn't lose against them."
Van Gaal could not resist a dig at Brazil either, after the hosts were destroyed by Germany in the other semi-final on Tuesday: "I think that losing 7-1 is worse than losing on penalties."
