For the NFL you can hear the QB radios, but they use voice inversion scrambling. I have also been told it's not just regular voice inversion, but rolling code voice inversion. These radios are set up in the UHF 461-465 area and are set up as repeaters. The officials can then kill the repeater if the coach is still talking to the QB at a time he should not be, and turn it back on again. They use DPL on those channels as well.
The coaches communication system is a Telex system. It uses WFM and the antennas are beams. You will notice the antennas behind the bench are pointed toward the other antenna. So you have to be in the beam width, close enough, able to receive WFM, and I believe its digital (Not C4FM or CQPSK) that is not decodeable (I think I made up a new word) on todays scanners.
The referee uses a mic, but I have not been able to find it yet.
Then that leaves the stadium ops, police ops, EMS ops, and media. There may be some public safety freqs that don't get used except for big events. NFL Films is always on the field, but I have never received them. There are usually multiple wireless field mics that are WFM as well.
Here We Go Steelers, Here We Go (I couldn't resist. I should have, but couldn't)
The games here in Boulder are not that interesting. Most of the traffic is about parking and traffic ops. There are lots of drunks that get ejected from the game, only interesting if you are one of them!