There are many variables that go into the physical appearance of an animal track. In your own words, "soft ground" can easily exaggerate the size of a track considerably, often by almost 50% in both dimensions. Still, you are obviously dealing with a large specimen. How certain are you that the track was swine and not cow or elk? Cattle have been known to raid feeders in the manner described, and I have heard many reports of elk that have become feral as escapes from some of the exotic ranches in the Edwards Plateau region. A larger elk could conceivably have done the dirty work.
More than likely you have a large boar (possibly with foot problems) who decided to use your feeder leg as a rubbing post. He put too much lateral pressure on the pipe and POP! the whole thing came down in a hurry. He was probably high-tailing it out of there when he left the tracks, which can also make them look bigger as well. Let us know if you ever catch up to him. :grin: