Here's my guess.
Clear Channel distributes the Steelers via a KU Band Satellite uplink on their roof, which is also received in Denver and repeated on Clear Channel's starguide system. Anyway, Clear Channel also distributes the Pirates Extra Innings show on this same system, so they don't have to pay Westwood One, which distributes the normal body of the Pirates games, for extra time. However, if the uplink is being utilized by the Steelers or Penguins, they bite the bullett and feed Extra Innings on Westwood One.
The uplink normally feeds WDVE's air signal when not otherwise used. So, I'll bet the Extra Innings operator didn't know, or forgot that the Steeler game was going on and changed the router to the satellite uplink to the WPGB feed until the calls came in from the affiliates. Obviously, this wouldn't have affected DVE's feed.
Don't ask me why they can't feed the steelers in one channel of the satellite sytem and extra innings in the other. It's a stereo signal. They do the same when Steelers and Penguins conflict. They bump Penguins to a different starguide channel instead of just splitting the stereo feed. They don't feed the Steelers games to the affiliates in stereo anyway, although they air in Stereo on DVE.