It's not like he picked the DR out of a hat, it's his family's heritage and he spent a good deal of his childhood there. And don't try to tell me that the DR team is more "loaded" than the American team...they just have more national pride and work better together as a unit than America. If you put the 9 best American players on the field, they should be able to wipe the floor with ANY team.
Pitcher - CC Sabathia
Catcher - Joe Mauer
First Base - Lance Berkman
Second Base - Dustin Pedroia
Shortstop - Jimmy Rollins
Third Base - David Wright
Left Field - Ryan Braun
Center Field - Josh Hamilton
Right Field - Matt Holliday (plays in left, but corner outfielders can switch easily)
That team could beat literally any other. The problem is many don't feel like risking injury, whereas players from other nations actually feel repping their culture is important. If the guys listed above don't want to play, that ain't Arod's problem.