France and Argentina are the highest-profile casualties of the World Cup where anything can happen.
"I think a lot of it has to do with the games being played some place else - the top countries aren't adapting real well for whatever reason," said Kasey, preparing the the USA's final group game against Poland.
"Everybody seems to be playing okay, but none of the big boys are really stamping their authority on it. It's been a strange World Cup so far, that's for sure."
South Korea and the USA could see to it that another big footballing nation, Portugal, books an early flight home.
"We could definitely do that. Portugal probably have a bit of momentum from the last game, but just when you think one of the big boys is starting to pick up - they slip up and get bounced.
"South Korea is a tough prospect for Portugal, they have to go and win against a hard working team. I'm not putting anything past this crazy World Cup though."
The USA's opponents, Poland, have perhaps looked to be one of the weakest teams in the World Cup so far, but Kasey says they can take nothing for granted.
"Well... next to Saudi Arabia I think. Poland haven't clicked, but it's always a dangerous time for a team like us playing the last placed team. We can't start thinking we're already through because we're playing a team that's out.
"There's still going to be a few twists left, so we know we've got to go out and perform if we're going to go through.
Korea we're very unlucky against us, Brad had a good game. We only really had a couple of shots and no corners in the game.
"We defended after we got the goal, rode our luck a little bit and were a little bit unlucky but, for the most part, were happy to come away with the draw."
Kasey Keller suspects that the pre-tournament hotly tipped nations just haven't got to grips with the World Cup being played outside of the traditional strongholds.