Ronaldo Forgot to quote your post
Instead of snowballing useless toplaners, junglers should be focused more on shutting down the midlaner. In the current meta the successful junglers are the one's who can easily 1v1 and set up ridiculous gank opportunities (Leesin, Jarvan IV, Rek'Sai) where other junglers simply can't. If it's true that a
mage is giving your team more trouble than any other archetype that midlane can and has dreamt up then they're also open to these weaknesses.
It might be said that Azir and Ahri have easy escape mechanics. Azir much less so, he has a fixed cooldown on his one escape mechanic which takes 3 inputs to complete (set a soldier, move it away, E to it). Ahri, though, has been giving irresponsibly by Riot, a ridiculous repositioning tool ON TOP OF her massive mobility post 6. This is what I argue against. There is no reason for Ahri to have that and it pointedly made it so that Riot had to over nerf her IN DIFFERENT AREAS THAT MAKE HER LESS FUN TO PLAY just to keep her in line.
Mages also have a power curve that as a line would have a slope of something like 1/1 until snowballing. If someone is known to snowball (Ahri, Akali) you can take them early and make attempts to farm/roam/catch out more often than they do with someone like Leblanc or Zed. If someone is farm heavy you can try a poke and sustain game (Lux/Syndra v. Ziggs), or opt to kill them repeatedly (Leblanc/Zed v. Ziggs). If someone scales hard into late game (What we know Ahri does before Patch 5.3, Azir is top tier in this) then again you can abuse early game champions.
Speaking specifically Azir had problems with MASSIVE late game damage beyond that of an ADC and a mid game zoning phase. But any mobile champion with patience could easily out sustain his level 1-8 mana pool because he's actually very fragile without his soldiers and it takes until his first finished item to notice any significant damage. If he doesn't spam soldiers he doesn't benefit from early zoning and if he does he will eventually lose the uphill mana battle. So naturally they nerf his damage at all stages, his seige, AND HIS ZONE which was what was allowing him to reach his late game, so now he has less of BOTH.
Speaking specifically Ahri, she was given FAR too much utility. That much is obvious and I have no hesitation in admitting it. Giving her the movement speed removed any point of not having safety pre-6 and baiting her ultimate post - 6 then made no difference. The buff to damage on her W and Ulti (can't remember if ulti was actually buffed but I'm fairly sure it was) and the charm probably could have done enough, if not just forgetting one of the buffs altogether and just doing two of them for DFG compensation. But in response to her rise in strength, they beat her down possibly farther down than she was post removal DFG. By nerfing MANA COSTS instead of just removing what made her so ridiculously safe and "easy" to begin with and by nerfing two ranges (WE GET IT, THERE'S NOT MUCH SKILL IN HER W AND ULT BUT THAT'S HOW IT'S DESIGNED) was covering the distance between her DFG state and her buff state and then some. They also reduced the damage in the W to spite Ahri players it almost looks like (though we've seen it active in LCS and it does seem strong). So the real solution would be to revert the Q buff and reduce the damage of W and MAYBE ulti, to preserve her play but to nerf what made her a problem in the first place. I find it outrageously irresponsible to over nerf her now instead of just reverting one or two mistakes and making amends in other areas.
Onto items. It's no secret that mana regen has been nerfed for this season and chalice is no longer the dominating force it was from Season 2-4, only, manaless champions and energy champions were not nerfed. So now mages are even more so gated by their mana costs while Katarina and Zed get to dominate the role without effort. Whenever Riot looks at them they say "how can we nerf this champion without actually dropping their power? (Zed attack speed nerfs) Or, "How can we BUFF this champion?" (paraphrased from Katarina's almost changes in the 5.3 patch notes). So now we have Spectre's Cowl buffs to allow midlaners to get abused further by people they gank, possible lane opponents, and some jungler builds. In the early to mid game they will have even less of an effect.
Lastly, I want to say that Kassadin's nerf is a near perfect model of how to approach mages (though I'm not sure he himself can be called that, the philosophy still applies). They nerfed his q by 10 damage at every rank. That's something, but it's not out of control reflexive response to LCS domination and winrate spikes. It's careful, calculated, and precise --> How they should treat all their champions' balance.