Nunu needed a rework more than Ryze.

Debatable. When Nunu is overbearing, he's at most a nuisance in most pvp situations that's deceptively overwhelming at objective control. His being broken promotes strategic play. When Ryze is overbearing, he's he's an unstoppable force that can shut down players with no remorse and in general finds his home in unhealthy mechanics like button mashing and abusing ping. Both are pretty needy at their low points, but Ryze is a mess on his high.