While there are some drama class work on display, ever get your foot stepped on by cleats? How about getting whacked in the shin (or back of the leg)? It does hurt. Why does no one call a (American) FB player who goes down hurt a "drama queen"?
Yes, you can find examples in soccer of players who acted like they've had their achilles cut when video shows they've basically been touched by a feather (or not touched at all). Unfortunately it's part of the "gamemenship". Refs are supposed to card those they feel are faking for "simulation". Rarely gets used.
I think a number of players in the US game yesterday were having issues with cramping. That's why they'd be running, then sort of just collapse.