Port velocity may drop off, and even reverse, without actually tracking piston motion.

The entire rod ratio thingy is a conundrum. The difference in piston motion and position among all the rod ratios you would reasonably use in an engine (from roughly n=1.4 to 2.1) is almost imperceptible, yet the results are not merely obvious but wildly disproportionate to any calculations.
How can such a small change give such drastic results? Yet, they've been proven by tests for many decades.
Example: Harley-Davidson significantly increased the rod length (but not the stroke) in 1937 to improve peak power in a low RPM, low compression engine with small ports and mild cam.

There is a similar and converse effect @ BDC: a short rod covers a longer piston travel path (in inches) during the same amount of crank rotation (in degrees).
What this does it capture a larger percentage of the full stroke length with the same intake valve closing point. This (not overlap, or LSA, or duration) is what changes DCR with rod ratio changes: shorter rod, longer stroke, or both always has slightly higher CCP.