Originally Posted by User Name:

Whenever I hear the phrase...

"they were out playing ball"

...I would automatically assume baseball, but I just wondered if that was common, or perhaps regional, or based on some other factor.

How about other people? Is it just baseball to you? Is it some other specific sport like basketball or futbol? Or do you not understand it to refer to any specific sport, and would then ask the speaker, "what were they playing?" ?