Look at text. And at crowd scenes. There is noise on the text and crowd scenes (like the Pocono commercial) on the MPEG2 version that is not there on MPEG4.
ESPN will never be perfect (as I see some of the same mess on cable as on DirecTV) but when it was messy, it was messier on DirecTV than comcast (things like crowd scenes, blimp shots, high action). This should clean it up. I can see a difference for sure. The clock in the lower right pops off the screen, for example.
Have you got cable and DirecTV?