For action sports, when I didn't use manual mode I used aperture priority instead of shutter priority.
I use aperture priory to make sure the DoF stayed more constant and shallow to blur the background.
I let the ISO float (auto) but kept an eye on the value being used and on the shutter speed the camera was selecting.
The ISO won't change much unless the lighting changes, but image noise is preferable to blurry because the shutter speed got to long.
You will want the shutter speed to be at or above 1/500, unless you're able to catch the peak of action when 1/250 may be fast enough.
The key to good action shots is getting faces and the ball in each shot.
To do that, anticipating the action is the key and placing yourself so the action is coming at you.
I generally only used a monopod with lenses that had a focal length of more than 200 mm, since the minimum needed shutter speed of 1/250 satisfies the camera shake preventing shutter speed guideline of - 1/the focal length of the lens.
For 2 reasons with action shots, you want the camera to be low enough you are shooting at a somewhat upward angle:
1. It makes the players look more powerful and commanding.
2. It helps minimizes background distractions.
So for most of your shots you will want to be on or near the ground, on your butt or or on a knee.
I often used a Walkstool.
Walkstool Comfort 26 - inch XXL Compact Stool Portable Folding Chair with Case for sportsandtravel Photography