Personally if I were in charge of balancing Ryze. I would first revert the passive duration change. And then look to buff Ryze by giving him more armor, a slight alteration to his E to where the bounce radius was larger, but it only affected 4 additional targets and did less maximum damage. I would also probably give him slightly better mana scaling with his abilities (probably only 0.5-2% increase based on ability). I would implement these changes slowly over the course of multiple patches to gradually bring Ryze up.
If I have to keep the passive duration change, the thing I would have to do is increase the CD of W. I would bring it to 16 or 17 seconds so one could not permanently root his lane opponent at level 3. I think that having a higher CD at early levels of the skill and then at max rank having it be down to its live 14 seconds might work, but if that were the case, I would have to reduce the root duration to 1.5 seconds or lower because people would still max W first and Ryze's level 9 would still be ridiculous. Right now you have almost no time at max rank W to get away from Ryze. Giving someone that .25 seconds to even just flash away would be important. The problem is I don't know if even that would be enough as Ryze has the duration of his W to reposition and catch you with another snare if you try and dash away. It will probably help but I'm worried it might not help enough for Ryze's opponents. And anything less than a 1.5 second root as your only form of CC at max rank wouldn't seem strong enough to be very impactful.
But I would see if that worked at first. If it did, that's great, but if it didn't I would probably have to stick with the higher CD on W even when at max rank. If this were to happen though, I think I would have to increase W's damage a little bit as instead of coming out every 4th spell in his passive cadence, it would be every 5th spell. Meaning his damage potential instantly becomes much lower. I would probably have to increase the damage on his other abilities as well to compensate on his damage cadence being off.
Right now Ryze can use the following cadence WQEQWQEQ.... repeating, using his ultimate at any point really, but I like to use it either before the passive is procced or use it to help me proc my passive a second time with almost no downtime. If his W CD was increased to 17 seconds, his new cadence would look like this WQEQREWQEQ, 1-2 seconds WQEQ. I doubt you could get that all off during his passive given you have to wait an extra 2 seconds to do nothing but AA or reposition. This wouldn't be the worst thing but in those 2 seconds you can almost get a full rotation of WQEQ with the live values. So if we just look at base damages he's missing out on about 500 damage (again just in base damages) at level 18. We could maybe subtract 1 spell cast from this but it would still be 300 damage lost (before items) from Ryze's passive duration. So I think it would be appropriate to give him some more damage in his abilities if his W cooldown is increased.
These are my thoughts on the matter. Thanks for reading. Peace.