Read dizus’ reply. I think I can add to it though...
The forward hole changes the angle of the link bar. If the link bar is angled upwards in the front, the rotation of the housing (or the force trying to do so) forces the axle downward, effectively causing chassis separation. More traction. More shock needed to control separation.
If you could get the front of the bar low enough, you could theoretically cause the chassis to squat, even with the same instant center location. (Spring eye)

A simple way to visualize this...
Try pushing a car with a 20” long pry bar. If it is parallel to the force you are applying, the pry bar will move the car without pushing your arms up or down. Now try pushing the car with the pry bar at an upward angle. The more force you apply, the more your arms will be pushed toward the ground. That same effect causes separation with the Caltrac bar.