With that said, ECU has always had a chip on it's shoulder.
It's not in the big four (UNC, NCSU, Duke, Wake) and has struggled for years with feelings of being "little brother". Think Utah State but with a lot more success. In the past it's taken threats of legislative action to get State and Carolina to play them. The big boys figure there's nothing to gain by winning and a lot to lose. And they have lost several times (ex. the series record for State/ECU is 16-12). In addition, State/ECU got so ugly they had to suspend the series for a couple of years.
They also are not a destination school when they get a good coach (Pat Dye, Bill Lewis) they lose them to (Auburn via Wyoming, Georgia). But they have had success against, for example, VT (series record) 7-13. They've put players in the pros. They're a lot like BYU, off the beaten track and on the outside looking in.
I think BYU should win, but if ECU wins I wouldn't consider it an upset.
For further comparison, they're 4-11 against UNC, 5-5 against Duke, and 2-6 against Wake. Notice how few total games there have been. The local schools don't really want to play ECU.
I was happy to hear about the series and hope to attend next years game.