Outdoors at night means poor lighting usually. Higher ISO results in more noise (grainer images). For sports action you want to focus on shutter speed primarily IMO - and want it to be 1/250th or higher with 1/1000th more useable in my experience. There are more experienced soccer shooters here but that's what I try for with my son's soccer games (U10).
Also, the more you can position yourself and anticipate the action the more likely you are to have a great shot. Add in a Monopod and you might just have some really good shots.
Best of luck