Limitation of my LED TV or OTA signal?

My first guess would be your OTA reception. Especially if you don't see it on other stations that broadcast sports OTA. Affiliates are not required to broadcast the same quality 720p/1091i signals throughout the country. We have OTA only and for the most part, OTA broadcasts are sharp and clear, with no issues at all. Is your antenna indoors or outdoors (rooftop) because that can, and will, make a big difference in reception quality especially, if you're on the "cliff" for some stations.

This does sound like a reception issue and not a tv issue (which is good, I think). Can you try different orientations for your antenna? What you may want to do is go to TVFool, put in your address and see what stations are local to you and their orientation. Then take your question, and the TVFool results to the HDTV forum that is specific to your area and see what other OTA folks are using for their reception. The best possible reception scenario is an outside antenna on your roof as high as is reasonable (typically 30' from ground) with a rotor. However, a lot of people can get very good reception indoors so it all depends on your area (how far you are from the towers) and what is around you (trees, mountains, tall buildings, etc). The OTA forum specific to your area will be the best place to go.

Signal strength meters on tv's can be misleading because of the way they calculate what they call "signal strength" so just use it as a guide but nothing definitive. You can be receiving 100% signal, but if the quality of that signal is only 20%...........

CBS sports broadcasts are in 1080i and Fox sports are in 720p. this means that motion blur is more likely on CBS then on FOX. since there are actually 30 frames per second displayed instead of 60 fps on Fox.
The higher the interpolation level more and smaller objects get interpolated causing more artifacts.
Pixelation is caused when all of the data transmitted is not received due to lack of bandwidth since not all partial frame updates are received. You can also get dropped frames if your OTA digital signal is too strong as digital tuners do not frames when the signal is too wear or when it is too strong..
How far are you sitting from the TV?

Are you sure you didn't write that?? It's seems scary if you didn't judging on the way it was written.

1. It's a LED driven LCD TV, "LED TV" is is misleading marketing term,
2. As long as you have a solid signal, it's not your antenna or lack of a better one. I can't say I have ever heard of an antenna in a garage,
3. Turn off off those 'gimmick' features and see if that changes things,
4. Do you have another set you can make a comparison with?
3. Can you post some screen shots?

Unless a particular picture quality problem shows up consistently on all channels/programs it's probably not the fault of the tv set. Networks and local broadcast stations all apply differing amounts of digital compression and the quality of the picture from different cameras used in the production of sports programming can also vary a lot. the fact that the problem changed depending on whether the camera was zoomed in or out should have been a clue that this was production related and not a problem with the set--simple logic.