Vince McMahon had quite the hard on for Brian 'Crush' Adams in the 1990's, giving him several pushes and characters. But nobody gave a fuck due to the man putting on boring matches and mediocre promos. He had a decent look, some good moves and was quick when not bulked up. Yet he rarely worked an average match, even with guys like HBK and the Steiners. Ryback has a more marketable look and physique, not to mention better promo skills. Unfortunately audiences demand more thesedays and Ryback's singles performances are sleep inducing at this point in time.
Crush timeline
1990 - Demoliton Crush
1992 - Hawaii Babyface Crush
1993 - Japanese Heel Crush
1996 - Criminal Crush (after spending time away from wwe due to a run in with the law)
1997 - Biker Gang Leader Crush
Ryback timeline
2010 - Skip Sheffield
2012 - Undefeated streak Ryback
2013 - Heel Bully Ryback
???? - ?????
What will the next gimmick be?
Terminator gimmick in WWE
Re-defining his Skip Sheffield character
Gay Psycho

:
Probably all three before 2017