To me there are 3 advantages to pushing crankbaits. One is like G said, the ability to fish a shallow running bait deeper. Another is the ability to fish around cover. In some of the sloughs around here, there's no way you could pull cranks in a straight line. If you were only pushing cranks though, you could maneuver around the obstacles. And last is the fact that you can have more baits in the water without so many long lines behind the boat to become tangled.