First of all, post me a link to where you read the UFC commentary was taken from live fights...I think your just posting that up and asssuming it.
Secondly it would be very hard to take play by play clips from actual broadcasting games as the announcers are in all different types of environments, you usually need a good sound room to get good recordings, not random stadium booths... Not only that they would have to search and search for every type of line they want to use.
Lastly, EA should just hire talented voice actors, and/or proven play by play guys....Madden picks out guys...and they are obviously bad....yet they stick with them year after year...
Whoops one more thing...EA need to hire some new writing talent for the play by play...and some new sound guys who know how to edit sound clips to sound the same and to flow together better.
What we got now is a boring announcer combined with the fact you can tell each sound clip apart almost...that's horrible