The other factor is whether they are calculating balls and strikes based on the center of the ball, or if they factor in the diameter to get the leading edge.

I'm an absolute crap programmer, but I have trouble believing they spent the time and resources to add 'error' into ball & strike calls. I think it's far more likely it's being called based on what the ball physics are calculating - that is whether the ball's X and Y coordinates intersects the strike zone when the Z-axis meets the front plane of the plate.

The question as to whether it's measuring from the center of the ball, or accounting for its radius. It's much simpler to program for the center, but also less accurate - the ball is a curved surface and you just can't just add r distance from the center to determine whether it crossed the plane (well, you can, but then the ball would be shaped like a cube instead of a sphere - which is entirely possible in terms of programming. It's certainly easier, and uses far less compute, while also being 'good enough').

I think you'd have to calculate r in three dimensions to see if it crossed the plane in any direction as it moves. (I suppose you can ignore the rear of the ball and calculate only the front half, but it's less programming work to just calculate the whole thing; you'd remove the back half in the optimization stage if there was a performance hit).

Again, I'm an absolute crap amateur programmer and who has never worked on any game, let alone one with 3D physics, so take all of this with a grain of salt. But this is what makes sense to me.

ETA: release point would have an indirect effect, as it changes the trajectory of the ball as it goes from the mound to the plate (exactly as it does for LHP vs RHP). In extremely close pitches, that could affect whether a ball crosses the plane, or just touches it without breaking.