HHmm.....why would some have full screen and clear and others not? Could it be the difference between a cable provider vs. satelite?
That is not an issue that is solely limited to the broadcaster or carrier. Most newer TVs (made within the last 4-5 years) can be adjusted to account for the way a broadcaster or carrier delivers the signal. If your TV is newer, check out your remote. Look for a button that is labeled with something including the word size. That will likely allow you to adjust the size of the image onscreen. There would be a range of choices. Your user manual could give some direction on this. UniSports works best on both of my TVs when they are set to the Zoom 2 setting. It gets rid of the black bars altogether. If you have that option, you should be able to have the same result.
Hope you have the option and that this helps when you watch in the future.