Well, they can add features regardless. And can update it whenever.
I would think it would make sense to have one MLB app. That is free, but without paying is pretty much limited to basic features.
Then they could have an in-app purchase for premium (radio & video stuff) for $10 or whatever.
Then they could keep the same app and just keep updating it.
As I mentioned, I have both the At Bat Lite and At Bat 2009 app on my phone right now ... then when I get the new At Bat 2010 app I'd have 3 MLB apps on there and 2 of them will be defunct? That's seems weird. Rather than having the casual fan who maybe has an outdated app on the phone go and download a new app why don't they just keep one app, keep it always up to date, and make the purchased features advertised for those who only have never paid for each given years purchased stuff.