Define "unreliable"
When you say Gnar is supposed to be unreliable, do you mean: A) He isn't supposed to be able to reliably contribute to a win B) He isn't supposed to have reliable strengths (that is, what he's good at is inconsistent and partially out of the player's control)
The latest patch notes strongly imply that you've stopped meaning B and started meaning A.
[quote] When a champion based on unreliability becomes a staple competitive pick (where reliability reigns supreme), we felt like something was up.[/quote]
You cannot give the player the means to manage his unreliability and then say he's too reliable because people who are extremely good at the game are able to mitigate the unreliability (not just the Gnar player, but his teammates; is he "too reliable" if his teammates can play around it? Knowing someone is about to be really dangerous for 10 seconds and being able to make use of it is also a form of reliability! It doesn't take very long to build rage, and fights can be in the poke/dance for position phase for more than long enough to bring rage from low to "ready to blow"). Your argument feels like it is essentially "If Gnar is played competitively, he's too reliable so we're going to nerf him".
This is of course an absurd philosophy, since it basically boils down to "Gnar isn't allowed to be good". It also feels ignorant of what unreliability means. If a champion had a skill that did amazing damage and AoE once in twenty casts, that would be unreliable... but also something that can be used reliably by playing off of statistics - if you're on a poke comp, you can keep rolling the dice until it goes off big time, and then immediately engage hard to capitalize on the dramatic loss of enemy HP (and correspondingly that they're going to be off balance mentally). This holds true more or less for any kind of unreliability that can be seen and reacted to when it's on a high point (well, so long as the high points aren't still weak, or the low points are so bad as to render you entirely useless).
You cannot see a champion being played competitively and decide that means they aren't unreliable. Dice are random, but they're also reliably random. Gnar isn't even random, his changes are entirely deterministic (hell, crits have no impact on transformation at all even). Anything that is deterministic can be manipulated, and anything that can be manipulated is predictable. If you expect Gnar to have uncontrolled highs and lows, that's simply impossible without making him swing between high and low rapidly.
This leads to a different problem. It feels somewhat like you've shifted from wanting each form to have different strengths into piling strength on Mega Gnar and weakening Mini Gnar. The former leads to interesting gameplay, the latter leads to (especially with the latest nerf to Mega duration) long periods of feeling somewhat helpless punctuated by the occassional spurt of feeling strong (of course, with how easy it is to escape Mega Gnar with his low movespeed, and the visibility to everyone of how close the transformation is... this often feels like "hey I'm strong, but it doesn't matter because I can't apply it"). This is a marked contrast to the original statements of having different strengths between forms (mini is good as kiting, mega at brawling), but... honestly it feels like while Mega has remained a strong brawler, Mini just doesn't kite well anymore (more and more it feels like damage is entirely reliant on Hyper early on, to where Q is ignorable on its own)
As is... it feels like you've gone with A when you promised B, and the latest patch notes only seem to cement this.