The normal TA rainbow has the green marabou and wool head tied on top of the shank of the articulated hooks. This has the green back and head tied on the far side of the hooks, so the hook essentially sticks out the side of the fly.
I've only given it the bathtub test (first two I've ever tied), but it looks like it's preferred ride will be head flat (sideways) and hook down. A vigorous strip will cause it to try and right itself with the hook turning to the side, but it quickly goes flat again (hook down). The result should be the erratic behavior it was designed for.
Eh...just stumbled on this (ever google yourself or something you did?), and figured I'd offer my two cents worth – even though it may be long. This is a fly I designed whilst at the Great Waters show in MN with Kelly Galloup a few years back (I work for him). Kelly’s TnA is most definitely its MOM, Swimmy's father would be a Zara Spook. It took a few permutations to get it to work. It started as a simple TnA with a deer hair head (I love hair), but I started playing with cuts, and how they might influence ‘swimmability’, along with a bent hook to exaggerate the head being crooked. Now...as to how to fish it...its entirely up to you. It was originally intended to be a diving wounded minnow, but I rarely fish it that way now. It’s too random. Also, it fishes nothing like a TnA – you fish it MUCH slower.
Currently, my favorite way to fish it is with a sinking line of some sort (typically Kelly’s), typically a really heavy sinker if I'm fishing smaller rods (6wts) just to get it underneath, but now and then I’ll use a floater...its just that a floater doesn't move it well unless you're pitching a 10wt – I have yet to try a neutral line, but that just might the ticket. I'll also gum it up pretty good (chew on it) to get it underneath. I don't like it to float, but rather be more or less neutral about 2-3 ft deep. I fish it with short strips with distinct stops. I will sometimes move it 6" in a near full circle, twitch it, or move it with larger strips. It will tend to arc in the water when it is stopped – continuing momentum. During the strip it will move straight forward as it is static and attached to .015” or perhaps .050” if I’m fishing for muskie (they LOVE it). The more abrupt the stop, the better it seems to swim. I also will typically use a very small saltwater 40# barrel swivel (I know…heresy) midway down my tippet (can you still call .015” tippet?)as it will twist a fly line like no ones business. As far as it's behavior...erratic is a perfect way to describe it. Ever seen a Zara Spook. If you hit rhythm with it (use your rod tip to fish it), it will zig and zag back and fourth, and up and down...completely crippled and dying. You have to play, each fly is a bit different than the last.
With regards to why the hook is sideways...more hooking area as its not covered by hair. Any fish, with the exception of little tikes chasing, absolutely inhale it, so biting just one side hasn’t been an issue for me personally. I like a braided steel articulation wire. I have not tied it in wool, but I have tied it with craft hair instead of marabou to make it MUCH larger in the body (8’-9”). That worked on Taimen, but since I wasn't there, I can't tell you how well it swam, or anything else. Having said that, the commercially tied fly (Rainy’s) is a whole heck of a lot better with regards to fishing than my own. I tend to stack the head WAY to tight and it just doesn’t fish as well. Mine is prettier though – which by the way is a stupid way to tie a fly meant to catch fish. Also, I’ll notice that out of every dozen you might fish from Rainy’s, 2 or 3 will swim and fish MUCH better. If anyone ever figures out why…let me know.
The fly will draw very atypical strikes. I've had trout in Quake lake (MT) swim up to it, stop, eye it for a few seconds...rotate around it, look at it more, and then inhale it with one large flare of their gills from 4+” (reminded me of those bass videos at Cabelas). Savage strikes are a rarity. You tend to miss a lot of fish with it because you start laughing. It is NOT a good fly for fast water, but is great on slower water (The Green, The MO, The snake, etc) and lakes – I’ve had fish open their mouths and swim at it from great distances. You tend to be early on those strikes. It is one fly you can stop the fly with and not have them break off all the time. If there is a fish big enough, they'll eat it. I hope that helps…if not, I’ll go crawl back under my rock. ☺