The very early days were more robotic. Mr. Parkers woprkouts with peers and guides did not stop when he left Hawaii. As he continued to investigate approaches, these became influences that flavored his approach. Depending on where he was at in his own journey, the students learning from him would often reflect that flavor.
I've met and trained with a bakers dozen of 1st gens, many from different "era's" in Parkers development. Guys from the early Chinese Kenpo days have a flamboyant flair, with lots of speedy circles. The splashing hands influence is easily seen. The techniques are recognizeable ("Hey, that looks like Gathering Clouds, only flashier & more Elvis-like"). Often, cover-outs are signitory of era...Chinese kenpo flowery hands days, as the feet move, the hands are circling about like doing a hula. Later years, they either maintain shifts between complementary positions, or barely move at all.
Pre- CK, still a recognizeable kenpo tech, but very robotic and deliberate, with the moves looking more like a Shotokan BB trying to emulate kenpo.
Post CK...the emphasis switched to more positioned, pinning, and rolling checks; power somehow got de-emphasized, and some of the slappiness and hopping-around foot maneuvers became more emphasized.
Towards the end, as he was working on refining the concentric circles and directional momentum model, some of the CK stuff became more prominent, but without the wasted floweriness. The hands whip about more than in the KK or AK models, but have greater directional harmony and more solid authority than in the CK model.
Watch the old black and whites of Parker on Mr. Sullivan's site. Earliest days = robot. Then, late 60's/early 70's, flare and flash. Late 70's/early 80's, techno-focused speed stuff, but with almost no pre-chambering (AK). Late 80's, ...watch the old man, and watch Frank Soto, and watch for the similarities; Soto does a good job of emulating the concentric circles signature movements in his upper carriage. You can see the progression.
And if you get on the mat with Parker-boyz from different era's (guys who trained, then either broke off and stayed where they were stylistically, or semi-retired and then came out of the woodwork 20 years later like a motion time capsule), you can see the emulation of where Parker was at the time...you can date-stamp the decade they trained in by how they move.
Be good,
Dave