Have watched the coaches show as well and can confirm that Rex in fact drinks beer and eats chips and queso during the broadcast. As a previous poster mentioned, he holds the mic (headset) extremely close to his mouth, damn near swallowing it. I think he does this because he doesn't want to pick up any outside interference while at a loud restaurant. The direct sound to the mic produces something called a "proximity effect" and explains the exaggeration of the low frequency sounds in his voice and breathing. The best way I can explain it is trying to hear someone speak on their cell phone when they are outside with hard blowing wind into the phone mic.
My annoyance is with his voice. It sounds very nasally when he talks, like his nose is completely congested and he can only breathe from his mouth out of desperation. I wonder if that was how radio guys were trained to speak years ago? As long as he's been doing this, I wouldn't expect anything to change. Luckily, John sounds totally clear and fine and that is who you want to hear talk anyway. Oh well, no hard feelings to Rex, just constructive criticism.