I think it can be any one of the reasons listed depending on how you fish the bait. Using shad patterned Senkos like a fluke absolutely kills sometimes. If you're crawling it along the bottom in more of an earth tone type color, bass could definitely see it as a crawdad. Alot of the time bass are just dumb and eat it because it's an easy meal. That really subtle wiggle produces alot of fish too. Any of those reasons and more is my vote.

Jake