Going South
 

Meaning:	On a path to failure, failing.
Example:	Revenue has been going South every since we hired the new Sales Manger.
Origin:	South is associated with the downward direction, because that is how it is depicted on maps. North is up, south is down. Hence going south is going down. And down is pretty universally associated with poor performance (falling apart) as in airplanes, swimmers, bicycles, and revenue.