[MizunoJoe]

Does any of this data show that you can't have a constant handspeed? No

In fact, the Am #2 data show that you can speed them up, but you shouldn't! I'm willing to bet he's a Switter. Having dumped his accumulators too soon, he then stifles CF by firing his right tricep. The point is that it requires hand/arm manipulation to prevent their slowing in the uncocking phase.

The one most important thing which jumps out from the study is that good players delay their accumulator dumps, while ordinary ones don't. If you want maximum club head speed, you pivot lag #4, and then take #2 deep down plane before releasing, or better yet, increase it with down-cocking. The better you lag #2, the more the hands will slow down in the free-wheeling stage, provided you don't interfere.