It's been over 2 years now, Riot
has had a pitiful win rate ever since the end of 2014.
http://www.leagueofgraphs.com/champions/stats/gnar
Aside from a narrow peak at 50% at the end of 2015 (likely due to preseason changes just making everything a 50-50) Gnar has had about a 48% win rate for over 2 years now. He's been one of the lowest win rate champions this season, consistently at 44-47%. He's doing just as poorly as the likes of Azir or Ryze (https://na.op.gg/statistics/champion/) except he doesn't bring the 1v9 carry potential in challenger / pro play that required them to be dumpstered.
Why has this champion been ignored for so long, and relegated to such a weak state? He's DEFINITELY no more "cancer" than Quinn or Jayce or Kennen are as the top lane ranged champions so I'd rather not hear that excuse. He's not oppressive as many are.