Negative Sadhbala

Hi 

Has anyone got experience what it means if a planet has negative sadhbala? I have a client who has unknown birth time, but the time she suspects (recalls but is not sure about) is around noon EET. And I wanted to get a glance of planets' sadhbalas around this time, and was surprised to see mercury having -114 (-27%) sadbala. 

That's because it loses in war to mars and saturn. Date is 1st of March 1966.

This seems like something useful to rectify a chart. I know from personal experience what low sadhbala mercury means, but I wonder if something special happens if it goes negative?

Thanks