so essentially you nerfed Kog'Maw over all since revert

V6.19 Stats Base attack speed increased to 0.665 from 0.625. Attack speed growth reduced to 2.65% from 3.5%. Caustic Spittle Caustic Spittle NEW PASSIVE: 15 / 20 / 25 / 30 / 35% bonus attack speed. Bio-Arcane Barrage Bio-Arcane Barrage REMOVED: Bonus attack speed, maximum attack speed and reduced cast time. REMOVED: Basic attacks dealing 55% AD to non-minions. REMOVED: Base bonus magic damage reduced to 0 from 4 / 8 / 12 / 16 / 20. Target's maximum health ratio increased to 2 / 3 / 4 / 5 / 6% of target's maximum health from 2% of target's maximum health at all ranks. Target's maximum health AP ratio increased to 1% per 100 AP from 0.75% per 100 AP. Bonus range increased to 130 / 150 / 170 / 190 / 210 from 90 / 120 / 150 / 180 / 210. Cooldown increased to 17 seconds at all ranks from 13 / 11.5 / 10 / 8.5 / 7. Duration increased to 8 seconds from 6. NEW EFFECT: Cooldown now starts on-cast instead of at the end of buff duration.

He was OP, I admit that. He deserved the revert even though I really enjoyed playing 5AS Kog'Maw.

V6.21 Living Artillery Living Artillery Initial and stacking mana cost reduced to 40 from 50. Maximum mana cost reduced to 400 from 500. Increased cost debuff duration reduced to 8 seconds from 10. Base damage increased to 100 / 140 / 180 from 70 / 110 / 150. NEW EFFECT: Deals 0.83% increased damage for every 1% of target's missing health, up to 50% bonus damage (versus targets above 40% of their maximum health). Maximum damage implemented at 150 / 210 / 270 + 97.5% bonus AD + 37.5% AP. Threshold to deal double damage reduced to below 40% health from below 50% health. Target's below the above threshold take double damage instead of the previous modifier. Base double damage increased to 200 / 280 / 360 from 140 / 220 / 300. REMOVED: Triple damage below 25% health, previously 240 / 330 / 540 (+ 195% bonus AD) (+ 75% AP).

After his revert people began playing AP Kog'Maw, I stuck to playing AD Kog'Maw because I had a feeling that with increase in popularity Riot Meddler would throw a fit about the unhealthy-ness of AP Kog'Maw. The prophecy was true and they did decide to nerf him. What we have now is a flaccid poke and an unreliable execute as his R. Thanks for the lower mana cost/CD I guess.

V6.24 Bio-Arcane Barrage Bio-Arcane Barrage Maximum health bonus damage increased to 3 / 4 / 5 / 6 / 7% from 2 / 3 / 4 / 5 / 6%. Void Ooze Void Ooze Base damage reduced to 60 / 105 / 150 / 195 / 240 from 60 / 110 / 160 / 210 / 260. AP ratio reduced to 50% AP from 70% AP.

AP Kog'Maw was nerfed even more due to popularity. To force Kog'Maw into the botlane they buffed his W to encourage more people to play AD Kog'Maw. The incentive worked.

Kog'Maw Bio-Arcane Barrage (W) bonus magic damage lowered from 3/4/5/6/7% to 3/3.5/4/4.5/5%

Nerf without context, thanks Meddler. It goes to show that when enough people cry about Kog'Maw or any champion on the boards they will get nerfs that the community deems necessary. Talk about A-1 decision making. "But Kog'Maw out scales every ADC with a Recurve Bow hehe xd", so the decision is to nerf him? Why not buff early game champions like Lucian, Draven, and Jhin who are sitting at terribly low win rates to make Kog'Maw struggle to scale?

Statistics wise in NA Challenger Kog'Maw's win rate isn't as inflated as people make it. With double Kog'Maw's games Tristana has a win rate of 4% higher. With 100 more games, Xayah has a 6% higher winrate.

https://gyazo.com/111e93a72b933720d844eeaab6e90045

Sorry if the picture is too small.