Good Job, Riot. You Killed Kog'Maw.
He went from being a balance nightmare with DOUBLE ATTACK SPEED (How have CertainlyT, Ghostcrawler, and Scarizard not been fired, again? Are their blowjobs THAT good?) and scaling way too well with on-hit items (cough Old Rageblade cough) to having no reason to be picked again. In fact, not only did you revert the rework (already a pretty big nerf), but you proceeded to NERF HIM AGAIN IN THE SAME PATCH. Not only this, but his W seems to SLOW DOWN his attack speed for no reason.
I have one question to ask: What were you thinking? Did you actually think that, by just reverting his rework, he would be OP again and you would need to nerf him?
It doesn't take a PhD to tell you that pre-rework Kog'Maw was mediocre at best and heavily reliant on his favorite items (BoRK + Runaan's + Rageblade) being good to actually be good himself. Then, you rework him and double-down on his reliance for on-hit items. Then, because he's super OP (because obviously), you begin gutting him. You also begin nerfing his favorite items, yet because BoRK + Rageblade + Wit's End all still exist (and Braum), he's still super strong.
So, now you made the RIGHT decision to revert his rework. However, you decided to nerf his attack speed growth AND his W. His compensation buff: Very minor increase in attack speed for the first few levels.