Current changes everything ... stirs the water, therefore breaking up the thermocline and redistributing temps and oxygen levels. Recently, we have had lots of fresh water entering the upper (south) end of the lake and moving throughout the lake down to the dam, where it is dumping into Table Rock. Because the lake is narrower at the upper end, the current moves faster. There is also the turbidity factor, and dingy water never hurts a crank bait bite.
So unlike the lower two-thirds (north) end of the lake, the river fish are more evenly distributed from top to bottom, there isn't as distinct of a thermocline and the fish are more active because the water is more oxygenated.
So ... you can get a crankbait down to these fish. As for it being a lot of work, that's just fishing. Catching them consistently takes starting early, staying late and working like a dog every minute in between.