Here's how I would book Justin Gabriel's face turn-
During one of Nexus's beat downs Gabriel goes up to do the 450 and Otunga stops him saying "these idiot fans don't deserve to see the 450" which should get a lot of heat. Eventually just stopping him from doing the 450 turns into forcing him to do things, leaving him alone when the WWE team fights back and outright bullying. Eventually when Gabriel can't take it no more he fights back and then hits the 450 splash. If done right it should garner a massive pop and establish Gabriel as a star.
During one of Nexus's beat downs Gabriel goes up to do the 450 and Otunga stops him saying "these idiot fans don't deserve to see the 450" which should get a lot of heat. Eventually just stopping him from doing the 450 turns into forcing him to do things, leaving him alone when the WWE team fights back and outright bullying. Eventually when Gabriel can't take it no more he fights back and then hits the 450 splash. If done right it should garner a massive pop and establish Gabriel as a star.