What kind of "flex" do subframe connectors prevent?

[O'Neall]

This is going to sound like a dumb question because I'm not sure I can explain just what I mean... but here goes....

By what kind of "flex" I mean... in what direction? It would seem to me that two bars running lengthwise alone the subframe rails and unibody wouldn't really do much for crossflex (if that's a word... what I mean is flex that goes across the width of the car either straight across or diagonally), but would be better suited to prevent flex that wants to "fold" (like into a "V") the car like a hinge at the firewall.

I don't know if that made any sense, but my point is that it seems to me that preventing this up and down flex at the point of contact is all they'd really do directly by adding strength to that connection. Ultimately that strength would translate to added rigidity which would translate to some "crossflex resistance" (sorry for my lame terminology) I suppose, but it just doesn't seem that without "triangulating" them somehow that SFCs would be much good at preventing this "crossflex" in and of themselves.

Forgive my ignorance and inability to express what I'm trying to ask and explain... but does anybody know what I mean? And can somebody explain to me just what direction of flex SFCs help to prevent