There's something wrong with the PBE

By which I mean, the PBE is not accomplishing what it is supposed to.

The PBE is SUPPOSED to be a place to test changes before they hit live so upsets to the balance aren't unusually large, to find out how players respond to changes to see if they're fun.

What it appears the PBE ACTUALLY IS, is a place where a small subset of the playerbase can preview changes before they hit live. the PBE appears to be treated as too far down the pipe to actually change anything before it goes out.

• Lucian's range was reduced but compensated by giving him insane mobility and manaless dashes. it looked broken on paper, it felt broken on the PBE, people on the PBE said it was completely broken... riot released it in the initial state with no changes and for one patch Lucian was dominating bot lane even more than he typically does. Riot literally said "oops".
• Cassiopeia's rework was put on the PBE. Players on the PBE said it didn't feel like cassiopeia, nor did it feel fun. Players noticed there was a glitch with her cooldowns that destroyed her dps... riot released it in the initial state and she was literally unplayable for weeks, and then only figuratively unplayable for months (and still is) as she's been basically going through another full rework's worth of changes. I like how gutting her happened in the blink of an eye but you guys are being super cautious about fixing her, you wouldn't want cass players to start having fun again too soon.
• Azir was incredibly buggy on the PBE, people were sure that he would need more time before release because he was completely unplayable... riot released him on schedule and has been fixing about 10% of his bugs every patch while also giving him numbers buffs to compensate for the rest of his bugs, so when his bugs ARE fixed he'll need to be nerfed again.
• The new jungle was on the PBE, everyone said it was way too hard except for a select few sustain junglers... riot released it as-is and warwick is DESTROYING THE GAME IN ITS CURRENT STATE. Riot says they want to nerf warwick because he's obscuring everything that's going on, but it's obvious that stuff like udyr and volibear are only right behind him and they're going to need at least one more cycle of whack-a-mole before they can actually look at how the new jungle does and does not support different jungler champions. so we're looking at like 2 or 3 more full patch cycles before riot even starts to look at the new jungle in a proper test live setting for balance. doesn't the next season actually have to start some time?

A while ago Riot said they would start using the PBE to test much more dramatic changes and players shouldn't be alarmed because they were going to still be cautious with their testing. I believed them for exactly one patch cycle when i was wandering around forums telling people to ease up because of what riot had just said, and every change went through exactly like it was on the PBE, so I guess riot just forgot about that new policy.

I don't know if Riot doesn't choose proper test samples for their PBE group, or if players don't test properly because it isn't worth their time to play long league matches without IP rewards on their main account, or if the matchmaking is just thrown to shit because you have a smaller player pool, but it feels like Riot has been increasingly using the PBE as a scapegoat for awful changes that ruin the game because "we get better data in the first few hours on live than we do from weeks on the PBE" Maybe that means your PBE is fucked up and you need to figure out how to do testing so your live game will stop feeling like your testing ground.