Comcast gets the same EI feed that Verizon does. The quality is not the best. There are a bunch of channels crammed into a QAM. If you're having troubles with NBC along with Extra Innings you should probably call for service to check your setup.
Tonight my MLB Extra Innings reception is pixelating on all MLD Extra Innings channels. FiOS Tech Support unable to resolve issue. They state that they are not having a widespread problem according to their 'whiteboard."
For $200, these problems shouldn't continue.