Shouldn't have turned him heel in the first place. At least build it up before becoming a 100% heel. The whole "recap/explanation" segment as to why he turned on John Cena was well produced, but looking back on it, it didn't make sense at all. But from my understanding, Mark Henry was originally slated to feud with Cena, which explained why he won at Wrestlemania. But he had to take a leave to deal with his personal issues.
They could have built Ryback as a rival to Cena without turning him heel. I mean, he can perform heel tactics to Cena, but they went and made him destroy other faces too, which became stale and annoying.
They could have easily done it like the HBK/Hogan feud.