Tony,
I assume you are using AIServo for focusing and not one shot mode. AIServo is definately the mode I feel you should be using in this situation since this is what the AIServo is designed to support (moving subject).
The situation you have (indoor/poor lighting) is the most demanding on a camera simply bacause you don't have sufficient light. To compensate for the low light, you are forced to up the cameras ISO and lower the aperature to wide open which I see you have done in the above images. The problem with shooting wide open is your depth of field (DOF) gets very small.
With calf roping, you need a very large DOF to get the calf, horse and rider all in focus; unfortunately, shooting indoors makes this very difficult if not impossible due to the poor lighting. The only way I can see getting sufficient DOF for this scenario is to use strobes (I suspect this is not allowed to prevent spooking the horses) or you can increase your distance from the subject which is not really prefered since you would have to really crop the final image down to have a worthwhile final image.
With the above said, I think you have to pick what do you want in focus, the horse and rider or the calf. When you pick one, the other will be soft since it will be outside of the narrow DOF. I would use a single focus point and keep that point focused on the riders chest to keep the rider in focus and most of the horse.
The other issues you are most likely seeing with soft shots are the limiation of the cameras ability to focus in low light and some possible blur due to a low shutter speed. The 30d is a good camera, but it will struggle to nail focus in low lighting situations. This is where you would want the Mark III to improve on the focusing in low light. With the Mark III, you wil also be able to go to ISO 6400 which should enable a fast enough SS to eliminate the motion blur.
Your first shot is not bad (need to watch your horizons), the second looks like it might be motion blur.
Here is a shot I took recently using a 40D shot at f2.8, the main difference being the shot was taken outdoors with terrific lighting. WIth good lighting, the cameras have a much easier time of locking focus and you get fast shutter speeds to minimize hand shake and motion blur.
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Hope this helps.....