They say it about champs like Zed, that are crazy strong, but because they make #LC$BIGPLAY$, they are intentionally kept strong.
I just said that. Anything people think is "OP" is Riot playing favorites, anything they think is "UP" is Riot being stupid and nerfing champs the wrong way. Riot can't win, people are going to complain and blame them no matter what they do.
I think they could have nerfed both Zac and Elise in a healthy way, not nerfing them to the point that they are unplayable and then never looking at the champ again. Let's be honest, Zac and Elise were dumpstered before S5 lol. I could count on one hand the amount of times I have saw either of these played.
Zac wasn't competitive in S4, but tanky junglers in general were not that great. That's why they're trying to fix the jungle in general in S5; tweaking individual champs wasn't getting it done.
Elise was used extensively in competitive play through the first half of S4, so I have absolutely no idea what you're talking about with her. She got a series of nerfs in the second half of S4 that gradually made her worse, and then the S5 jungle completely obliterated her.
Champs are left to be unplayable for so long, yet they allow Lee Sin to completely dominate jungle play since I started playing the game before S3 just because he makes cool flashy LCS plays.
You see Lee a lot in competitive play because he is safe. Before the nerf to cripple (in the middle of S4) I thought he was overtuned -- he used to auto-win almost any duel against an AA-heavy champ at level 2 or 3. But now you have to be VERY good with him to do decently, and in solo queue he's generally terrible.
I agree with what Riot has said about him -- if they just nerf him numerically he'll be garbage. They have to change his kit around to give him better-defined strengths and weaknesses, but the prototypes they tried out weren't good.