Ryze isn’t doing too well following his rework, but there will most likely be brighter days for him.
His new rework is pretty tricky and Riot made it so you can't just smash your face on the keyboard and get a pentakill. You actually have to think about what skills to use to benefit you best at the time. This involves a lot of split second thinking that players just aren't used to on Ryze.
People also love to engage using his ultimate, which is not the best idea against a team comp with a LeBlanc and Cho'gath, as shown by this video from Reddit.
According to champion.gg, most champions don’t do so hot on their initial rework releases. They all typically dip down on release and then come back up the following patch. This is sometimes the work of buffs that Riot deems necessary or just players getting the hang of the updates.
Ryze already had a very low win rate before the rework, but the changes hit him harder than some other recently tweaked champions.
|Champion||Win rate before rework||Win rate on rework release||Win rate after rework|
Fiora actually saw a huge dip in her winrate, going down 10 percent when her new skill set was unveiled, but her win rate soared back up after players got used to her new kit.
Fun w/ stats: Champion gets buffed, winrate goes down. Why? More play in its worst role (whose WR also went up), lowering the average.— David Turley (@RiotPhreak) July 1, 2016
There's also the matter of people who don't normally play a certain position, like mid, for example, playing the new rework just to test it out. If a support main plays mid-lane for the first time in ages and does terribly on Ryze, that affects his winrate as well.
Either way, his winrate will either go back up from people adjusting to his new play style, or Riot will step in and give him some buffs.