Trout or Crappie Magnet - it makes no difference. Even the Split tail is not the key reason they work but the body/ tail action when imparted cause the lure to waddle back & forth. I make my own but the tail is a solid cone rather than split :
The design catches everything.
Design aside, no matter what color you chose, it will catch fish using a Magnet and light jig (unpainted of course).
As far as changing grub colors and starting to catch fish again, been there. It could be a renewed hope/confidence in the new color which translates to a slight but significant difference in how we work the lure. It is good to change colors and designs if only to keep things interesting.