[AtlUmpSteve]

Here's what I would add; not subtract, or change. What you have here is a good start.

For optimal consistency, set your eyes at the top of the zone you will call, and with your nose on the inside batter's box line. That sets two of the four parameters in space; anything above your eyes is too high, anything past your nose in inside. That limits your required judgment to the two remaining parameters; outside and low.

Secondarily, move closer to the catcher than the picture; no more than 6" behind the catcher, if you can. The closer you get to the front, the more you can see the ball through (and past) the plate, into the glove. The farther back you set, the more the catcher's body blocks what you want to see; it's basic geometry.

Finally, track the ball, as far as you can see it; with your NOSE!! Forget the eyes, don't worry about head movement, no matter what anyone else says. If you keep your nose pointed to the ball, your eyes will stay focused; and nothing is more important!!