I hope y'all understand these guys are told to talk about specific points and that it may not be their decision to talk about something as much as they are. Please tell me y'all are smart enough to know that. These guys have bosses too, and guys up top that give them talking points and do whatever it takes to get a rating and keep it throughout the program.
I'm experienced enough to know there's a huge difference in a producers role in a studio show and a live broadcast. You're mixing the two genres together here and it doesn't work that way.
In a three man "live crew," the only person that's "assigned" a storyline is the sideline reporter. A lot of those assignments are done in-game, not pre-game. (By a lot I'm saying more than 2/3rds.)
Why is there such a stark difference between what Greg brings to the booth and what Gary brings? Greg is doing his own research. Gary, in spite of the help he has, doesn't do much other than follow storylines. It's his choice to focus on the things he does--not a CBS producers decision. The same rule of thumb applies to all of your broadcast networks' live crews. He made the decision to go with his "11th man" narrative both in content and repetition.