Do you know for how long Jayce had over a 50 % winrate in 1½ year?
...1 week. His playrate and banrate is and always was both low. Can he please get buffed soon - he was actually in a good spot before preseason, but LW rework hit him hard, especially in Midlane. Maybe his Shockblast could get some armor pen, perhaps 20-25 %, as the poke even when fed does very mediocre damage when your innate armor scales up.
Alternatively, make him really tanky at the cost of some damage in Hammer form, making it a bigger decision which stance you are in
Manamune/Murumana buffs (stack time) are also very welcome. An active so your next skill does 25 % extra damage, at the cost of 25 % mana?
(black cleaver is good for his W on his cannon since you get can 3 shots so 3 stacks then switch to hammer and finish them) jayce is pretty bursty and snowballs veryy well. ive never really tried him adc just top and mid