The preseason changes have only made snowballing and general game momentum worse

And considering snowballing was already a big problem in the past, it boggles the mind that you would make so many changes that only increase its efficacy.

Let's go down the list, shall we?

Dragon & Baron

So I understand that you wanted the dragon to be a valuable objective that players clamour over and that causes some interesting plays to be made. And while it is true that it is certainly more interesting now than it was when it was merely another tower and some change worth of gold, there is one fundamental problem with the dragon as it stands:

Any objective located in the middle of the map is going to benefit the winning team more often than not.

In practice, very rare are the times where the losing team is able to catch up or gain enough of an advantage to be able to grab baron or dragon safely, especially if the winning team already has one or two or, gods forbid, three dragons ahead of them. If your team is too disadvantaged that they cannot reasonably expect to win a team fight there is no way at all to "ninja" the dragon, especially since the timer makes it way too obvious when the winning team needs to go check up on it. The dragon becomes a mostly-guaranteed bonus for the winning team and only helps the losing team further slide into irrelevance over time. (Note that this probably wouldn't be so much of a problem if the Dragon and Baron weren't so bloody mindlessly easy to kill. Giving them more damage could be a way to help mitigate this.)

Combine the above effect with baron and things start to look really, really hopeless really, really fast. There's effectively no way to recover in the grand majority of games once the winning team nabs baron. This is at least partly because...

Laser Towers Really Suck

We already have a thread on this but it bears reiterating: inhibitor and nexus towers REALLY suck right now. I mean, they are just pathetically weak. Completely awful to the point where a disadvantaged team doesn't even really gain anything from trying to engage under a laser turret because they'll all die long before the turret can actually do enough damage to turn things around. Doesn't help that turrets are so weak that minions can easily beat them down on their own without any champion help (and weren't these towers supposed to be helping with split pushers?!). I know you wanted to weaken turtling team comps but you've gone way too far here. The losing team needs SOME kind of help to get them back into the game and if towers aren't that help, what is?!

Inhibitors: A Long-Standing Problem

90% of games are already lost once the first inhibitor goes down.

Think about this very, very seriously for a moment. Is this what you want? Do you want games to effectively be decided once the base is breached for the very first time? I mean, 90% is a ridiculous skew. You may as well just end the game on first inhibitor kill instead of the nexus with a skew that heavy. Only 1/10 games will see the losing team bounce back after the first inhibitor goes down!

That's weak. That's really, really weak. Now, I know that the first inhibitor kill goes to the team that already had a winning momentum in the first place, so it can't all be blamed on that, but that is besides the point: when a single objective matters to THAT degree, it kills the spectator side of the game. Once that inhibitor goes down you're basically watching for that 10% chance of the losing team somehow miraculously turning things around. That's one out of every ten games where this will actually happen. It's not good. It's not healthy. It's horrifically demoralizing to the point where, if you're aware of this figure, you're basically hoping for a miracle to happen (or the surrender vote to pass, one or the other).

Part of this is because of the above objectives. Part of it is because of the above-mentioned turret deficiency. They all come together: Once that inhibitor goes down you have to put more resources towards base defense. Because you are busy keeping super minions from running roughshod over your nexus turrets you are at much greater risk of missing a baron or dragon kill, putting you even further behind. And of course your jungle is being farmed considerably less because you are on the back foot, only adding to the pain.

There are only two ways to really recover once you reach this point: you either win a team fight (or pick the enemy team off one by one, which requires really poor play on their part), or you split push. And if you are really behind, all split pushing is going to do is get you picked off by the winning team. You COULD try to turtle, of course, but as I said - towers are useless. If you were already at enough of a disadvantage to lose an inhibitor odds are very much against you winning a team fight even with the help of turrets.

So in summary, I think the game momentum was already heavily skewed towards one side picking up an early advantage and that this advantage increasingly grows stronger over time unless the losing team somehow miraculously pulls off of a momentum break somewhere (usually before the first inhibitor gets destroyed), and the preseason changes have only made this situation worse. We need more mechanics that help the losing team break the winning team's momentum and get back into the fight. The game simply loses too much of its excitement (and it is REALLY demoralizing to play) when you can effectively call the game lost after one objective goes down.

There are a number of avenues you could take to affect this.

Buff Baron and Dragon

Right now they do so little damage that it is not a deterrent at all in the mid-game phase - your only concern is the enemy team and if you already have an advantage you don't give a toss about them (if anything, you'd WANT them to engage so you could crush them further still into the dirt). Dragon in particular is completely free to the winning team mid-game and up - if the losing team tries to engage them on dragon it's really not far removed from trying to engage them anywhere else, possibly even worse because they'll have warded the area up in advance.

If, on the other hand, it did enough damage that the losing team could capitalize on it to try to win back some of their lost momentum, it would actually be interesting. Instead, right now, it's just too easy and free to be interesting on any level. Hell, given the strength of the dragon's buffs, maybe it should be impossible for any one champion to solo it?

Something to think about, at least.

Buff the towers!

Self-explanatory. I can understand concerns about game length but towers should at least be strong enough to help losing teams bounce back in a tower dive team fight, rather than being a complete non-factor. If you intend for them to be weak against minions then perhaps giving them some kind of true damage proc (possibly based on % health?) would help.

Give the losing team some kind of ability or buff on inhibitor loss

Because, let's face it, 90% of the time the game is decided when that inhibitor goes down... and that's just boring.

It could be something like a special anti-siege minion that the players manually activate with a cooldown of X amount of minutes. It would be powerful enough that it could possibly (maybe!) turn the tide of a team fight or let the losing team nab a turret or two, but the loooong cooldown means they have to support it or it's completely wasted, giving them an actual decision to make. Do they pop it immediately as the winning team starts to go to town on their nexus turrets and hope for the best? Perhaps they let it go down the lane and split push, forcing the other team to focus on one or the other? Or do they go down its lane and use it as a mobile tower?

And of course, the threat of such a minion would force the winning team to consider whether or not they want to take that inhibitor or if it's better to try to take out more inner turrets instead. Remember that the winning team already has a considerable advantage and loads of momentum at this point - even with a powerful helper the odds are very much against the losing team making a comeback, but having that sort of help dramatically increases the tension at the later stages of the game. And if the losing team manages to take out an inhibitor, now they have to deal with the same thing!

I understand something like this brings up concerns about closing out games and the like, but that is a question of priorities. What's more important to you: having a game where anything could happen at any moment, where the winning team is not GUARANTEED a victory once they gain enough of an advantage, or having a game where matches close out more quickly because of that momentum? I know where my priorities lie.

And of course, this is just an example. There are so many other potential avenues to take for potential momentum-breaking abilities and the like, and I trust Riot to be able to figure that stuff out. There is no question in my mind that there needs to be SOMETHING, at the very least, to make things less hopeless. Rewarding players for skilled play is one thing - absolutely crushing the losing team into the dirt with momentum-based mechanics is entirely another. Let's try to reduce instances of the latter, yeah? Everyone benefits from that. Even being on the winning team gets boring when you're just grinding faces into the dirt.