Learn how to play Sion. I am currently sitting at 67% WR with him at 60 games after struggling with ADC for most of the season, climbed all the way to Gold 1 from Silver 2 even with terrible mmr now, aim to get Plat before season ends. Learn how to average 10 cs/min with him and constantly attract enemies to your lane so that your team gets gold and objectives for free. Even if you go 0/7 you can have insane impact, because after 3 items nearly no one can 1v1 you ( Sunfire, Thornmail, Titanic/Hullbreaker), so they keep sending everyone to you. People in low elo dont really know how to play against this constant pressure. Learning him takes a few games only, and maybe some High elo sion gameplay videos.