The case with Roman Reigns is that They have not built him credible enough to make me cheer him. I have liked him since Shield. He is a powerful brawler and has a par arsenal of moves. He is not good on mic but I can survive the mic problems. WWE is trying to make me cheer him everytime but it feels like forced one. The guy despite a powerful one is given an underdog-esque booking.
I cant tell surely about what crowd was doing with him. I just know Ambrose and Brock are hugely over and crowd wanted most probably Ambrose to win it. When they did see Reigns winning, there starts the boos.
I need to say that Reigns need to be built as a dominant silent heel who is just there to destroy people. Once He is an an established heel, then the face turn will really make people cheer him naturally.
By the way, Did someone noticed the pop Ambrose received when he tried Dirty Deeds on Reigns at RAW? It makes the whole thing clear.