Those of you slating Reigns need to realise some stuff.
First of all, he did AS HE WAS TOLD by Brock, who was calling the match. It was very obvious the strategy, "I'n not giving you many openings, but when you get one you SHOOT...hit me as hard as you can". Each time, he bloodied Brock a bit more, playing into his "if he bleeds" mentality... then Brock told him to use the ring post to play off of Brock's only real "weakness", concussions at Mania... and he did, Whether he was legit concussed or not, Brock SOLD that and THEN Reigns got his chance.
Why it went down this way who knows? Maybe Roman DID fail Wellness and this was kind of the punishment. Maybe Brock balked at losing to Reigns but was happier for Reigns to be pinned after proving him human... Maybe Vince saw what Rollins did earlier in the night, turning the dogshit Randy Orton was producing and turning it into gold and said "fuck it, we're going with this guy". Brock didn't lose out and neither did Reigns here.
Reigns flaws were exposed in the match, by design... he hit too many Superman punches and Spears, part of his arc now is that he can incorporate that into his story, he finds a mentor or manager who teaches him more, a killer submission for example...so that next time he can be more prepared... If Zybysko didn't seem a bit flakey at the HOF he'd have been perfect for it.
Reigns proved he has progressed a HELL of a lot in a short space of time, but Rollins is clearly WAY ahead in all areas so it's logical he got the nod over Roman... If they're smart, they start repackaging Roman slightly as of now, get him in better shape so he can ditch the vest... get rid of the Shield music/entrance, give him some more moves... Then not only is he in the hunt, but he's gonna start making some clean kills.