I honestly feel like he's not as bad as he seems on paper. He does have a really low winrate which probably means there is a problem with him right now, but I think some of this might stem from people not adjusting to new/changing masteries, changed items, and a new meta.
Can I ask what Runes, masteries and build path you are using right now? If you check any site on that, they usually have the most popular items on him being Cinderhulk (not sure which enchantment), and then Deadman's Plate and Righteous Glory being some of the items that are bought often on him. A lot of streamers who are jungle mains run this kind of build on Gragas and AP/Tank champions like him right now as they find DMP to be the most efficient HP/Armor item and Gragas is fairly mana hungry in the early parts of the game (and really still in the lategame if he builds no mana and gives away blue buffs). But I don't think this build is really the best setup for Gragas, particularly in solo queue (below Diamond primarily). Disclaimer: I am NOT a Diamond player; based on streams and playbacks of players in that bracket and above, I assume they have a lot more organization than lower levels.
Anyway. I have some ideas about how to improve on your Gragas game based on a little experience and some calculations. I do think he needs a little tweaking to make him more of a solo queue champion rather than just being viable when you have reliable teammates to work with you (more competitively viable due to organization). I think some minor stat changes and some tweaking to damage on his Q and W is the way to go (maybe touch on his E a little too). He doesn't need a lot of help really to be extremely viable in a solo lane right now as AP item changes favor him in a big way right now. A slight increase to minion damage on his Q would be all he really needs, but there is a risk of this being abused and we will see the old non-interactive Gragas mid/top that just sits under tower when he's behind and never loses any CS. We'll see what happens though. Peace.