The light is very directional. Aimed. They will have a light meter and measure every bit of the field to make sure the stadium lights cover every bit.

In doing so there can actually be an area right under the lights that is quite dark. A ball hit thru that area under the lights could be difficult to see. It illuminates the underside of the ball. So they have to illuminate under the lights pointed up as well. Lights are only too bright if you are looking up at them. So they dont illuminat from the light to the ground. Instead they illuminate up so you are star gaze blinded look up into that lighting.

My father owns a Sports Lighting Business. All he has done for 35 years is install lights all across Texas. I grew up doing it with him.

I can confirm those are ball tracker lights. They shine on the bottom of a ball. If you don't have them, the ball would be shadowed underneath, and if a player was looking up, it would be a black ball against a black sky. Impossible to see. The upward facing lights give it just enough where you can see and track a ball in flight from ground level.