It's true that you'll need higher ISOs to reach the shutter speeds necessary to minimize motion blur. Under those conditions, you probably wouldn't see a huge benefit from using a monopod. However, a monopod will help tremendously in those situations where the players are relatively still (during a timeout, or else waiting for the ball to be thrown in). When those situations arise, you can turn down the ISO as well as the shutter speed in order to get a better quality picture. However, in doing so, you'll need a steadier hand (or else a good support mechanism). That's when a monopod would certainly help.