Ball joint are normally tested unloaded... . you have to unload the suspension to test them correctly... All ball joints have some play, your mention of 3/16 to what I think your trying to say 6/16" = 3/8" is excessive if it allow the top of the wheel to move in or out, and or the side of the wheel to move in or out... in either case, this in and out movement will cause the vehicle to track incorrectly and will also allow excessive tire wear. .
As I remember, we used to check a ball joint with a dial indicator and the maximum play was something like . 060-. 120" so your are bad... . I actually went to the moog sight lookin for updated information but couldn't find it. .