I may be wrong, but I don't think TS is looking for a multiple shot stroboscopic effect and may have said so.
Again, I suspect it lies with your flash settings (and because of the way EX and ETTL was designed and programed to think and operate - it's the direct opposite of how say, SBs were designed to think and work).
Short Version:
TRY THIS
Don't change anything else just yet.
Keep it the same for now till you start getting that 'CLEAR' frozen image within that sea of blur, then start experimenting with darker BGs, different shutter speeds, subject wearing different coloured clothes etc etc etc
Either
bump up the flash compensation - a LOT if you still want to work on E-TTL till you get something close to what you want,
OR switch the flash to MANUAL output, and start experimenting with output (1/1, 1/2, 1/4 etc) till you get that clear, sharp image that's lit by the flash.
Don't bounce if you find that you don't have enough light or start opening up your f stop a bit, or increase your ISO a bit.
I'm just guessing based on what little I know of the EX system at the moment.
Forget that photo of the swish of blur and a razor sharp playing card for now.
Also listen carefully to Catchlight's suggestions. He's very, very experienced with light, flash and getting results that work.