Ernie worried Carlos exacerbated his existing calf injury against Chile and so didn't play v Korea:
http://www.stuff.co.nz/sport/football/9652165/Measured-Merrick-clears-the-air
(last paragraphs):
"Merrick will have Costa Ricans Kenny Cunningham and Carlos Hernandez back from international duty to meet Adelaide, although he's not sure what sort of nick Hernandez is in.
Cunningham played the full 90 in Costa Rica's 4-0 loss to Chile and then came off the bench in their 1-0 defeat against South Korea. But Hernandez only had 60 minutes in the first game and none in the second and Merrick fears he might've tweaked the calf that was injured in the 5-0 mauling of Melbourne Victory.
The pair arrive back in Wellington late tomorrow night, before the team fly out to Auckland on Wednesday morning to begin preparations for Adelaide."
Match report:South Korea's goal scored by one of the tallest players in their national team history, 1.96 m. (6' 6") Kim Shin-Wook.
Two Costa Ricans sent off.
10 mins video highlights: http://www.youtube.com/watch?v=NPfqLRcg0z4
Fan footage of game by CR supporter - skip the few minutes intro - rest is (shonky) match footage:
http://www.youtube.com/watch?v=AnK1UkzA2Cc
Tiny crowd in vast stadium. American football goals still up behind the football goalposts!
I think Stuff got that wrong, numerous sauces say Costa Rica made about 5 subs that game, including bringing Carlos on in the late stages.