Viktor was the laughing stock of the mid lane mages for a very very long time. When they reworked him, it took a while for people to get used to him as a champion. I personally think he's in a good spot, and that the nerfs they are giving him are not in the places they should nerf (cough cough, get rid of the unnecessary tower destruction on his Q)
But regardless, he is an immobile caster mage and it takes a while to figure out if those of that class have too much or too little power, as their weaknesses are probably the most clear out of any other.
Personally I think Zerath should also be looked at.