I do think too much is being made of having a MARTA station nearby.
Thanks to local politics/racism, having MARTA nearby does very little to serve the majority of Braves ticket holders - who all live in areas that are not serviced by MARTA. SO it does not help much to connect the stadium to a station, if the fans can't/won't use it to get home.
Obviously fans could park further out, and take MARTA to a game, but it would still be a hassle getting to and from those stations in North Fulton, and most suburban Atlantans are conditioned to "needing" their cars, and have an aversion to using MARTA.
I lived in Atlanta (Cobb County), and worked in mid-town and buckhead, from '93 to '01, and rode Marta maybe a half-dozen times - a few times during the Olympics, and a couple of times to get to the airport. Otherwise, I had no use for it. I had season tickets to the Braves in both Fulton County Stadium and the Ted, also had season tickets for the Falcons - never considered using MARTA for any of those events