Take that Charlie Gibson!

The moderators for the fall Presidential debates have been listed, and it looks like ABC didn't make the cut this year.
Going back to 1960 when the first televised presidential debates were held, ABC has moderated more debates than any other major network, seconded only to PBS.
Now it seems that the lineup this year is very visibly close to 2004's debate setup, with Jim Lehrer (PBS), Tom Brokaw (NBC), Bob Schieffer (CBS) and Gwen Ifill (PBS) each taking the reigns this year as moderator in that order. (Gwen Ifill will be moderating the VP debate.)
This mirror's 2004 but for one difference, NBC veteran anchor Tom Brokaw seems to have replaced Charlie Gibson, who moderated the second Presidential Debate in 2004.
Now I wouldn't read too far into this, I'm not exactly sure on the exact details on how these things are negotiated, or how far in advance they are planned, but I found it interesting that Tom Brokaw has not moderated one single debate. You would think a heavyweight such as Brokaw, a household name by any standards, would have had his chance in the past, but interestingly enough NBC has only hosted one other debate in the history of televised debates and that was back in 1960.
Perhaps it is Tom Brokaw's expanded role as political interrogator extraordinaire ala his new position as temporary host for "Meet The Press," replacing the legendary Tim Rusert, or maybe NBC is trying to play up it's news and politics credentials, both with hosting the Olympics and expanding their political coverage to be on par with the other networks, as seen this winter/spring during the grueling primary.
Or you know, it could be that people watched Charlie Gibson and George Stephanopolous' wincing performance in Philadelphia back in April and someone up the chain decided: "Gibson's out! Brokaw's in!"