Its almost impossible to tie KE directly to passthroughs because there are a nearly infinite number of variables that come into play with each shot on game. Differnt angles, different situations, different size deer.... the possibilities are endless.

There are guys shooting these things off crossbows and not getting passthroughs on does, then you have guys shooting 60#s and blasting right through deer at 30 yards..... variables.

You'd have to develop an objective test. Set up a number of bows with descending/ascending KE and shoot at a consistant media and measure the penetration. It would take cow hide, 1/8" plywood and probably 7-10" of balistic gel with another piece of 1/8" and cowhide on the other side. Thats about as objective a test as I can think of.