I bought this new lens about 6 months ago and have been trying different settings to make my action shots not blurry—sometimes they are and sometimes they are not. I'm finally using manual mode, shutter mode, or aperture mode as I also use to use auto focus. I've increased my shutter speed to 1600, my aperture at f/2.8 and I've done different things with my ISO anywhere between 100 and 1000. I take pictures from the stands, and games begin in early evening when there is still a fair amount of natural light and then progressed into stadium lights.
You have to tell if it's motion blur or focus blur. Since at 1/1600 on people I doubt it's motion blur I'll assume it's focus blur. I see three factors that could cause this:
- Wide aperture on long focal length: this reduces the depth of field, if you use a smaller aperture (bigger number...) you increase the chances that your subject is actually in the sharpness area. If you are using f/2.8, 1/1600s, you have some margin.
- AF method: this depends a bit on you and how you use the camera. If you are using the half-press/focus, press/shoot method, there is some chance that the subject has moved in between. A continuous tracking AF mode could get better results. I don't know the specifics of your camera but some cameras have a more precise central point A/F sensor that can be used on lenses that open at f/2.8 or more (the measure is done at full aperture so you can use smaller apertures and still benefit from this). If so you can disable any kind of zone AF to make sure the camera will only use the central AF sensor.
- Accuracy of focus of your camera: your camera's autofocus could be inaccurate (consistently wrong) or imprecise (random values around the correct one)(*). Try shooting a few fixed objects in the stadium (lamp posts, stairs),in the same conditions (stairs are a good way to tell if your camera suffers from front- or back-focus, just remember which one you aimed at and see which ones are really in focus). As for #1 if you use a smaller aperture, you can somehow compensate for this.
(*) Personally I have improved all my lenses by changing the camera body...