I would say limited upload bandwidth and possibly catcher settings to blame. What's your upload speed from your slingbox to your slingcatcher or are you streaming locally at home? If so, that's a whole different problem. If your slingbox is at a remote location; what screen settings do you have the slingcatcher on.....320 X 240, 640 X 240, 640 X 480, etc.. Sports can be the most difficult for remote viewing, especially if you have limited upload bandwidth. More information on your end is needed, but it could be both of those reasons for why your picture is blurry and choppy or it could be that you have the catcher set on its maximum resolution without the internet upload speed on the slingbox end to view it, thus the screen becomes choppy.
callinish is right. It makes a huge difference with the upload speed at the slingbox location as well as how good your download speed is. I'm streaming from California to Germany and mine looks great. Here's a quick video of what it looks like: