The first thing I have noticed is the incredible diversity among the teams. There are a total of 32 participants and all the (inhabited) continents are adequately represented.
Well, it's called World Cup for a reason 
FIBA made sure that each region/continent is well represented.
What is going on with American national basketball team?
A lot of players have given up from playing for the national team at the World Championships.
Personal commitments to other stuffs and maybe some of them are already satisfied with winning the previous tournaments. Don't worry about them, hungrier players will replace them so it's still good.A lot of players have given up from playing for the national team at the World Championships.