He already have so much damage potential. One of the main issues in league of legends right now is the DAMAGE and it's high scaling and how even bruisers can one shot other champs. Increasing damage in one shot potential champs like 
just will make matters worse
Because the last fizz change with W was mean't to be a NET NEUTRAL CHANGE. Not lose half his playrate and have his win rate drop by 5% or more. As a result, they are buffing him to fix their balance mistake. Simple, there was no nerf. Since it ended up being one, he is getting buffs.
More than half of the marksmen roster sitting as trollpicks but hey lets buff another assassin game isn't snowbally enough.
because he is one of the worst champ in the game rn
Honestly, fizz is in a bad spot since the changes and deserves some buffs. However, whether the current buffs on PBE are the right way to go about it is a different question entierly. I for one think it's a bad idea to buff his upfront burst, especially by as much as they do. I'd rather see him getting a bit more damage into his W-dot, some help with his mana, and maybe some more defense, like an ap-scaleing on the passive(so trinity-bruiser won't profit from the increased tankiness)
Increase maybe his defensive stat so he can keep aa while dealing sustained damage rather than burst?
Fizz should be deleted from the game. Ridiculous champion that shouldn't exist in the first place. Same goes for 
These buffs gonna make him ult bot.thats all
Fizz does need a buff after his w change since that was most of his damage I not seen any fizz do good after the change and I know a burst and assassin Meta so why buff him but that it the change made it he can't burst as in an Assassin's main job what's the point of picking him if you can't one shot after this W change and it's not like he has a lot of safety to fall back on to normal when an assassin has less burst they have more survivability or an easy way out I feel like I good example of safety versus burst is Ekko. Ekko does not have as much burst as most assassins he can normally only one shot you if he has Proto belt and Lich Bane but in place of burst he has safety his passive gives him move speed to run away after going in. His Q lets him Farm safely from range and push up the wave. His W is a shield not much more to be said. His e is a short cool down Dash though it is small and his ultimate is either a big safety net or burst. But fizz has no safety he is purely melee so he puts himself in a lot of danger when going for Farm. His Q needs a Target so it's much harder used to escape his w is just an auto buff his e is a lot of his damage but his only real safety spell so if he uses it defensively after the W change he's lost another big burst if he is offensively then he has no real way out and his ultimate which is basically all his damage now after the W change so if you survive that he has to wasted e they he has nothing left he No Escape no damage nothing he's just going to die so after losing most of his burst he is so bad now. One lost thing I don't play the slippery fish but I do know a decent amount about the champ to be honest I enjoy playing with and against Fizz so it's kind of sad when he's really weak.
I think they should have never touched him to begin with. He was starting to see play when they started tweaking him, and with his kit and how tilting it is, he should never be allowed to be "good," along with Tryndamere
the assasin class is probably in for another class update,most likely after the LCS patch.
Because he has to compete vs Zed so buff more dmg to fizz. thats how riot does balance
because people keep complaining that he is weak like the aatrox rework, they just need a couple of days to figure out how to play his new w
i love how some pepole say that only wukong and nocturne can 1v1 , and other assasins cant , it's not like it's the bruisers job to be good at 1v1s besides assasins kill anyone who is squishy(or even tanky as it seems in this meta) how i view the game is assains being super broken to add fun to the game (cuh cuh) , then adc mains who consist of little crybabies start crying about buffs , adcs get buffed and everyone suffer
this buffz are fking dumb fizz is after the changes officially broken and u wont love seeing him everygame
