Well after going to a game, 90% of staff were using various models of Motorola DTR radios. So they're un-monitorable.
DTRs are fantastic radios with a great building-penetrating FHSS technology. The DTR line is really underutilized in my opinion. These are ideal radios for schools, hospitals, office buildings, small to medium-sized stadiums and amusement parks, industrial plants, warehouses, hotels, etc.
I use DTR radios as our family radios around the neighborhood and while traveling. The penetration throughout a ship during a cruise, for example, beats out my analog, DMR and P25 radios. Glad to hear of a stadium using this great and cost-efficient digital technology.