Why Kog Mid Isn't a Thing Anymore :(
The changes to his ult. basically kill the poke style many AP Kog mains enjoyed. Moreover, an on-hit build is way too slow for mid and also doesn't fulfill the role's requirements. If a mid laner lacks significant CC, they need great waveclear and poke. Kog's lane is more punishing than ever but even if you get your items, your team rarely has enough peel/CC to allow you to be effective. Burst, waveclear and poke are what mid-lane is supposed to contribute if you want to win.
The old Kog variant was not only stronger in lane but provided better burst and poke while also scaling way better as a reward. This allowed him to contribute to the team somewhat safely barring engages and gave windows to come back too. Now, if you have to get into 710 range for 6 seconds with no hard CC, no defense and only mediocre damage output, all of Kog's weaknesses are amplified 100 fold. However, due to the nerfs to his ult.'s damage >50% HP (as well as increased cost and duration until mana reset), you are forced to use W a lot more even in AP builds just so you're not completely useless. This makes mid-lane extremely unforgiving and his early was weak even before the rework. If you have to play such an unsafe style with him for a meaningful contribution, W needs to scale way better with AP or have a higher base damage.
No one really asked for a Kog rework and we weren't asked for feedback regarding its direction. It's not fair to change him so drastically that one of his favorite lanes actually becomes uncompetitive in ranked. I've played hundreds of AP Kog games and he's my favorite champion.
There are many other Kog threads with suggestions. We'd like some direction and all our favorite lanes to be viable. Although, I will say that the changes to W probably make Kog JG nearly viable (if your team can survive 20 min. without losing too much) and that's something I've tried a lot before the rework with pretty unimpressive results.
We're still waiting.

Hi Koggles
Yo.
How's it going?
Has anyone seen my move list? I can't remember how to use finalas funkelm.