If you don't want to read my ramblings..you can get straight to tldr, didn't expect it to be a wall of text :).
I was placed in Bronze IV in March. Until Bronze I-II it was relatively easy (I could feel I am better), however, at Bronze I - II the level of play changed drastically, it was harder. I got a little stuck there (about 2 weeks). However, I qualified for Silver V, and again I felt that the play became easier...people just didn't play well. Qualified for Silver IV and was stuck for like 3-4 weeks there...no idea what the cause might have been but then luckily got to Silver III and strolled through tiers in like a week until Silver I (again, was very weird how fast that progressed, didn't notice any change of the level of play between Silver IV and Silver III-II). At Silver I, I again noticed a change in play of teammates. People became more aware of the game, and I could literally see that the players KNEW what they were doing. It was a very drastic change and very very noticeable. Even if we lose, I notice that it wasn't due to a player who doesn't "belong" in his tier or due to 1 player. It was because of the team as a whole. It would just be because of a bad teamfight or someone would get caught or my fault for not hitting that crucial bubble as nami etc...I wouldn't even feel bad because of loosing really cause I knew everyone was on par with each other and blame for the loss is because of "us" not "you/me". Maybe I just got lucky..but to me the game became much more enjoyable. Although I also noticed I am paired with Gold V - IV players which may explain that drastic change (and me saying low gold level in title).
In terms of mentality, here is my observation. In Bronze people would blame each other in pretty much similar ways...with stupid things like "report vayne" (for bad play ONLY!), "report this, that"..."stfu".. "omg, no ss/mia, report" etc etc. In Silver, "no ss/mia" and "report this/that" persisted, however, with a rare explanation of why. And sometimes explaining "why you go top, stop splitting, group with team"...frankly grouping with team is probably the biggest problem of mid Silver tiers (imho)...people just go off on their own inducing rage of the rest of the teammates. That is my observation.
In Silver I and Low Gold, here is what I noticed. People NEVER say "no ss"...EVER. (at least I haven't noticed it)...people are much more aware of their mistakes and say "MB, sry" when it is really their screw up..in Silver and Bronze there were times when someone said that, but usually I felt it was just out of politeness (since sometimes it wasn't entirely their "MB"). Also, on a negative side, people there are cocky. They feel they are really good and like to show it off by cryptic information/messages (maybe I haven't grown to it yet)...its hard to give an example..it can be something like "nami use heal, 2 for 1 is worth", upon which I would say "I was oom, it costs 130 mana lvl 5 heal"...and then "you dont understand what I am talking about .. lol"...some stuff like that haha (real example). Shot-calling is much much better, and objectives are priority..kills are priority only when we/or enemy is stomping. And I often do say something like "wow" (in a good way) aloud cause of the amazing play my teammates/or teammate make. Hence it is a very noticeable change and I am happy being part of it.
Bronze IV-II : Level of play is low, never your own fault but everyone else's ... its always the team... everyone requires you to "ss/mia". "Report vayne/insert champion"
Bronze I : Level of play higher, same mentality as above.
Silver V: Level of play lower than Bronze I, same mentality.
Silver IV-II: Level of play higher, mentality is mostly the same with additions of explanations. Grouping seems to be the biggest problem here (imho).
Silver I - Low Gold : Level of play MUCH higher, more mature mentality, people are cocky with cryptic messages, sometimes dismissive.
I main support, and what I noticed gave me more wins was always keeping track of my KDA in op.gg. Having 10/8/4 may look like a good score...but that is a KDA of less than 2.00 (very low imho) and costing your team. Having a score of 1/3/11 (KDA 4.00) is a much better score than 10/8/4. Of course, its not in every situation (looking at split pushers and tanks and maybe carries who NEED kills even at their own expense to carry), but as a rule, high KDA = higher success and less of a burden to your teammates.
This helped me to get out of Bronze and hopefully soon get out of Silver (I am extremely close).