I am not sure there is a "standard" for ball position at address. I know alot of instructors in their specific teachings feel that there is, but I think it is more on a personal level for the individual golfer, and his/her's swing. Myself, I play the ball in the center of my stance 90% of the time. The other 10% is for shots requiring high, or low trejectories. Green side shots, I might make an adjustment. Shots from uneven lies are also cause for a ball position adjustment for me. GJS