A Civilized Analysis
Following the nice request from Lao fu The Tiger, here is a post with a more civilized approach on some of the current perceived issues in League. Disclaimer: I do not claim to be the best player out there, but I will still try to take a scholarly approach and make more of an argument than just facts and statements. Highest personal ranking is: Silver I 100 LP solo, Gold V ranked 5v5, Platinum II 3v3. I main the bot lane (both positions) in all maps. I am playing on a regular basis with high Platinum to mid Diamond players. And for some reasons, despite the luck factor, I win more than 50% of my ARAMs. So, despite not being a high tier player, here is a rational analysis, without any rage.
Lets take a step back. The change to mana regeneration had probably much more ramifications than what was expected. Standardization was a very good point and points towards an easier to understand game and an easier to balance model, but it, voluntarily or not, shifted the entire standard build of mana mid champions from Athene's Unholy Grail to Morellonomicon. Regen on morello seems at the moment better adapted, and it also provides the same cooldown reduction along with almost the same amount of AP and a nice passive. What is does NOT provide is the 25 MR from the chalice. Now champions like Ahri never traditionally focused their build on Athene's, and rather went straight up for the now removed Death Fire Grasp or even Rabaddon's deathcap. Because of her bursty nature and the squishy nature of most mid laners, her power spike with a Morellonomicon completed is amplified with the fact that Athene's is no longer built, leading most AP mid laners much more susceptible to the burst; 25 MR less is still a lot of effective life gone. The natural defences for most mid laners being gone, the safest burst mages are expected to soar, hence in my opinion the true origin of the Ahri situation. Removal of the DFG just standardized the rest of the bursty assassins, but one point in the data is still an outlier. Also note that, while DFG was very strong on Ahri, it also led to a lot of overflowing damage. Now her numbers are much more tight and the 100-0 is technically more difficult to perform. So, in practice, yes she probably is the best of the remaining bursty mages, but she is not in any ways out of a reasonable number range.
And then, the situation got hectic. Remember I talked about that 25 MR ? The thing is, experienced mid laners may be able to hold, but giving her a kill can rapidly mean a sneaky snowball. And lower defences favour Ahri. The charm can provide just enough lockdown for the burst, who, while being not as bursty, will be quite effective on a low MR target.
Yes, it won't be a hard snowball, but a sneaky one that will abuse another fact overlooked by many players: the bot lane experience skew. So, the bot lane is technically always under levelled. A slightly ahead mid laner can even exacerbate that to a difference of 3 levels with the bot lane with the right timing (2 levels is generally expected, 3 can be achieved with very good instinct, and 4 is frequently seen if your mid laner give a kill or 2). And this can happen even if your bot lane didn't die. One of the classic skew, is to get a roam from a level 9 mid laner while you just got your 7 (lets stick to a very conservative 2 skew). The most important consequence of this skew ? In the case of Ahri, it implies a max Q, but it's not probably the most important problem. The problem will often be the health advantage. Frequently overlooked, the total health provided by the levels can easily lead to the common situation where a dive leaves the opposing team with slivers of life. It is not entirely the perfect execution that saves people: it's also the raw amount of health. In many cases, a roaming mid (lets stick to Ahri for now) will get the kills, add the XP to his levels, accentuate the skew and quickly lead to a situation where the opposing mid laner becomes the dominating factor of every play. It smothers every decision to this simple question: will I get ambushed, or flanked or otherwise dived by the mid laner (also note that if all your lane didn't got rolled over, the mid laner can pass Go, and collect 300g on all of them). In the end, lane dominance of mobile mid laner assassins can lead to an undue pressure on side lanes performing well, just because of the sums of small details will make a big difference in the end.
To summarize, Ahri's kit is fine, her laning is probably ok, her mobility is annoying, but only because it's mobility and mobility get on our nerves from time to time, but the scenarios and the world in which she exists makes her stands out. In the end, it's always a referential problem: the world shifted, but Ahri, and maybe a lot of other champions like Zed, Jarvan IV in the jungle, Kalista as adc, didn't. The landscape started to drastically changed with the beginning of Season 5 and the change on Athene's, and slowly. the ripples led to the Fox standing out.
The mitigating arguments: is it really a problem ?
Other factors have also led to mid laners such as ahri to soar. Supports in the bot lane have had a tendency to become more play makers and less about the protection of the carries. This leads to easier assassinations. A corollary is that the overall spectrum of summoner's spells is more diversified, leading to teams opting less for exhaust and sometimes for double ignites. Guess what fox hates exhausts more than ignites ? The overall vision as also see a trend to diminish a bit, with junglers sometimes not warding and most top laners and ad carries not buying pink wards. In a meta dominated by less mobile mages, those details matter less. But dominated by mobile assassins, 100g is sometime well enough to catch a bad roam. While Locket of the Iron Solari was and is still popular on Taric, most supports favour aggressive items over the defensive Locket (with the global MR aura and the shield). And I guess the list could go on.
The bottom line: maybe counter-play should begin at champion selection, and maybe even in blind pick opting for the safest course of action can help tackle down mid laners that appear to be outliers. Still, if they get a lead, they may be a little bit too hard to put back in check, and things can get out of control in their favour without reasonable counters or possibilities.
Overall, to state that Riot does not commit to balance would do them an incredible injustice. I believe though that getting the big picture and anticipating ripple effects (like the one I believe Athene's caused and still echoes today in the present situation) is very hard, especially when dealing with the balance of a game at many different levels (from Bronze to Pros). But, keeping in mind the bigger picture could lead to more practical solutions, while preserving the mobility, flashy style of many champions. Analysing side effects and maybe aiming towards rebalancing unrelated issues might be a better solution to stop the ripple and make the game, simply, enjoyable.
Fellow summoners, I hope you can share a vision on these thoughts, and not just sophisms.
See ya all on the Rift,
Tekalion
P.S. Please forgive the infrequent grammar mistakes, I'm not a native speaker. P.P.S. Yes, probably I could have given more thoughts on other connected issues, but this post just got way too long for the initial intent...