floating a dead bait of the bottom

[Dick Dastardly]

I think most experienced predator anglers have found a paternostered bait more effective (in general) than a float suspended one but I wonder why this is?

 

Wecome to AN by the way Old gh. Do you use an uptrace with that rig (never seen it before and it looks quite interesting) or in reality does the line above the swivel actually lay more along the bottom than vertical (well near vertical) as the diagram shows? Also what species do you normally use it with and live or dead baits?