Fielder approaches play in a balanced and aggressive manner taking short strides.
As the ball is played, the fielder is perfectly balanced, in alow coruched position, weight on the balls of the feet, with the head still and eyes level.
Experience may allow a certain amount of anticipation.

Fielder assesses line of ball and moves at speed onto a line slightly to the non-throwing side of the ball.

Ball is picked up between the feet.
Head over the ball, knees flexed, body and hands low.
Side on to the target.
Watch the ball.

Throwing foot passes behind non-throwing foot (The Crow Hop).
As throwing arm swings back and down, upper part of front arm is used to sight target.
For shorter and extremely fast throws the back foot may not pass behind front foot, but be brought up to or along side front foot.

Strong throwing position established.
Target sighted.
See throwing example.