Lost the Last Three Ranked Matches; What Do These Matches Suggest?

So I'd say the major problem I see is lack of pressure. In the majority of the games you play there isn't much objective control, and your damage isn't just crushing people to the point of shutting them down and being able to end the game w/out barons or dragons.

The garen game you did well, but no one else on your team did, so you didn't find a way to pressure other lanes, and spread your lead to a team lead. If you can't use your advantage to win (either split push like mad and win w/ your team being weak, or help snowball other lanes/shut down their lane opponent), then you depend on your team to carry you (even if that just means them going even and everyone working together as a team mid game).

The sej game is an even clearer example of this, no one on your team does well really and all the other lanes got ahead, which makes sense looking at the 14 assist amumu who was probably involved in a lot of the kills his lanes got that set them ahead. Also they took two dragons, which shows that at least a little they were pushing to turn their lane advantage into an objective advantage.

The vayne game your team lost their lead in late game and then lost the game in super late game. If you have the advantage you have to learn how to press it and end the game, or you risk this happening bc you're relying on your team to win once the advantage disappears, which is less likely since you didn't win w/ the advantage.

The vayne game you won before these is a good example of how you're relying on your team, 7-5-8 isn't a bad score where you really know you got carried by your team, but look at the stats and you'll see malz and shy carried hard that game. Malz had the most damage to champs by far, and shy had pretty good damage, a ton of damage tanked, and put out enough pressure to keep all the lanes in the game or winning.

The 6-2-7 Lis game might just have been something you couldn't win bc of the team, but w/ tp you probably went top and there are like no kills top lane, so if you used tp and got the kills before team fighting started then you tried and just couldn't keep your teammates in the game. However, if the kills came during team fighting, you need to exert more pressure when you play top, take tower, roam, invade jungle, whatever, but either snowball he hell out of that island by killing someone who's being ignored up there w/ you, or force someone to come top to help them out so the rest of your team has an easier time and doesn't get so behind.

You definitely have some decent games, but you aren't exerting as much pressure as you need to in order to win games w/out relying on your team. Also you may want to consider not playing ADC, or playing something other than vayne. In every gam you have on vayne (wins and loses that I saw in your last 10 or 12 games) you have some of the lowest damage on the team (only looking at damage to champs since that's all that matters). If you're struggling to get close enough to do damage on vayne, you may want to look at an ADC with more range to do some work in team fights. Otherwise you'll only win games as ADC if your team carries you.

If you want an example of what I mean by exerting more pressure, look at the xin zhao in your lissandra win w few games back. He was jungle and had a stupid amount of kills, but he got every single lane ahead, and he almost did as much damage to champs as mid, top, and the ADC combined.

Bronze is all about being able to finish a game. So often people don't know how to end when they're ahead, and often they don't control objectives well either so you can push and steal barons or dragons or stuff to get back in the game and have a chance to win, even though your team got behind and should have lost. Learn to pressure objectives, and spread a lead in your lane to other lanes, and you'll be able to do well.

im only bronze so feel free to disregard my opinion though ive been on for 3 or more years your team frequently has no dragon control and what ever fights you are winning you may be backing to before getting a tower rather than getting the tower then backing as the closest lane to the dragon bottom should keep a ward by dragon.

with someone like vayne, you're positioning has to be really, really good because of the short attack range. also, having GA and banshee's is a bit much for defence (and you lose a lot of offence because of this). only one defence item is really needed. instead of one of the defence items, you could go BT (botrk and BT gives massive lifesteal and the bt shield plus bt gives 80 ad).