I think the "boomy" problem is due to the fact that the microphone is actually mounted directly to the goal. The vibrations from the ball hitting the rim or backboard cause the mics diaphragm to vibrate, causing this low frequency.
BTW, before anyone on here tells me that I'm wrong and "how dare I for posting inaccurate information" I need to tell you that this is pure speculation.
That's what I was thinking at first but the music in the arena as well as the ball hitting the court were affected. Also, the Booming wasn't present in the stereo feed we were getting in the beginning. I am thinking that they are mixing the ".1" of the 5.1 incorrectly.