#3 The coalition with Paul Heyman is the only change in Roman Reigns' character over so many years
Until Roman Reigns showed up at WWE SummerSlam recently and allied with Paul Heyman on this week's episode of WWE SmackDown, he had pretty much played the same character for many years. Look at Seth Rollins, a man whose career has spanned the entire length of time on the WWE main roster as Roman Reigns, and how he has gone from the Kingslayer to the Beastslayer to the Monday Night Messiah, and compare his career trajectory to Roman Reigns, who has been the same guy from the first day.
WWE believes that any performer, be it Roman Reigns or someone lower down the card, is over as long as the audience cares about cheering for him/her or booing him/her. As long as they are indifferent towards the said person, he/she will not get over. This was the risk they ran if there wouldn't have been a shift in the personality of Roman Reigns and thankfully, the coalition with Paul Heyman serves this purpose.