Tapered Stroke Variable width

You can do this with a single Shape Layer path, trim paths, and a taper on the stroke. The first step is to draw the path starting closest to the camera (bottom left). Next, spin down Taper and set the end width to something you like for the end of the path. I chose 20% in this example. Then select Shape 1 and add Trim Paths. You will want to animate the end value from zero to 100. 

The trick is setting up a linear expression that modifies the end width from 100% to 20% as the trim path draws the line. To make things look better, I selected Round Cap. 

Here's the expression I used to start the taper when the line is 40% complete (because of the arc).

t = content("Shape 1").content("Trim Paths 1").end;
linear(t, 40, 100, 100, 20)

This is the result:

The screen recording shows the taper starting at zero, but you can make it start anywhere along the line. I think a constant taper looks more like the ball path you see when the PGA broadcasts events. I hope this helps.