WWE has a big day on July 31 because they have to announce their WWE Network subscriber numbers during their conference call. If The Undertaker comes back at Battleground and there's a lot of buzz generated online, some of the people that aren't subscribing right now might sign up for free for the month of July. The month of August may not be a free month for new Network subscribers, so if that's the case and Undertaker is back on Raw to promote a match against somebody then suddenly that $9.99 Network price tag seems reasonable to people on the fence. Even casual fans know that The Undertaker isn't a full timer anymore and never will be again, so if they want to see him have another match they better sign up for WWE Network. That's a big reason why WWE is bringing him back because they know he'd be a boost to those numbers that they have to report in two weeks time.