Firstly, it's very hard to change direction between pressing and releasing the pass button, so the change of direction is very minimal but does matter.
If I have time now, I'll make you a video just to prove it. Unfortunately, I'm working.
Have you done some test? What tools did you use?
EDIT: I was able to find a footage that I saved yesterday.
If you can't change direction while you're pressing the shoot/pass, why is the arrow on L2 shot still moving?
You can, until you release the button..then power bar stops, arrow locks.
It's just "minimal" that we can't see it real time.
That "minimal" change of direction might the difference between hitting the post and scoring a goal.
Tho the minimal levels of adjustments almost doesn't matter? Because the game corrects your inputs, according to snap zones.
I feel like this is a good visualization of snap zones:
At least when I play, I think of each player having a zone around them, and there's 8 quadrants in each snap zone that I can play the ball into. But of course, some quadrants the player is more reactive to the pass (matching his stride), but for other quadrants (ball played behind him, for example), he would ignore my pass, or have a little trouble finding it at least.
That's the extent of control I have. I can't really fine tune it much more, unless I play to free space (no player in that area = no snap zone). Or maybe if I use L2, tho I'm not sure, snap doesn't activate initially, but still activates AFTER the ball is sent.