I have caught a couple of crappie in my lifetime and there are 2 things that I never do. One is use live bait (minnows) and the other is trolling. Now minnows will catch crappie and people can catch crappie while trolling, but....those techniques are not for me. I just don't like fishing like that.
I'm a fool'em rather than feed'em type fisherman. I'd rather catch 1 crappie that I have cast to than to have every rod jerked down while making a trolling pass and catch 6 or 8 fish all at the same time. Where's the fun in that? Either feeling the crappie take in a plastic grub, tube, minnow, assassin, or watching the line jump a little or tighten up or move off sideways is where the thrill is for me at least.
If I don't catch Crappie while casting to them, then that is ok too. At least I have had time to hone my feel for what the jig is doing, even if it doesn't make contact with a fish. BTW, there are times when you can catch more fish casting to them than while trolling with spider rigs too.
My advise to someone wanting to learn to crappie fish, especially a bass fisherman, is to fish with 1/32 oz jigs, 4 lb test hi vis yellow line, 4'10" to 5.0' ul rod, and fish sloooooooowwwww. When you think that you are fishing too slow, then slow down just a little bit more. There are times as the water warms up when you can speed up a little bit, but all in all, you can't fish too slow for crappie. Crappie like to ease up on a bait, eye ball it for a spell, and then suck it in. You usually don't get the violent strikes that a bass will give you. Many crappie bites are so subtle that unless you are watching your line and have ultra sensitive touch, you would never know that you had a bite.
My theory is that when you feel a crappie thump the jig, he is actually trying to expell it from his mouth and it gets snagged on the lip area. Most of the time when a crappie inhales a jig, you never feel it. You just see the line tighten, or move slightly off to one side or the other or the line will just twitch with no feel communicated up the line to the fisherman. If you set the hook when you see the line tighten up, most of the time the jig is hooked in the back of the throat in the roof of the mouth. My definition of a theory is this: A supposition based upon ignorance of the subject matter. emoBigsmile emoGeezer