Just because you do well with him doesn't mean he's op. Maybe he's just easy to play, not many people know how to deal with him/haven't encountered him, maybe you have been lucky and have been matched up with derp opposition.
Hec also has one of the worst passives ever and is never usefull in terms of utility.
Also a positive k/d does not mean that you are good. I had an ashe that would only use her ults to steal kills from afar. She went 12-9 and was one of the most derp adc's I have ever seen.