It's not about establishing credibility it's about generating an emotional response to get clicks, etc. These morons know the Cowboys have the largest fan base so the easiest way to generate attention (which is their main incentive) the more likely they are to hold onto their jobs/salaries.
The networks don't give one fuck about objective analysis, they just want to generate attention, and they don't care who the one holding the megaphone is that does it. They know stupid fans think former players automatically know what they're talking about so that's why you see so many of them on TV, but if they could get away with any random moron up there riling people up they would, i.e. Stephen A.
The majority of these people talking on TV now are nothing more than highly paid shitposting trolls, and the networks themselves are basically just social media wrapped up in a different delivery vehicle.