I was a diamond 1 player last act and this act too. I was excited to push to immortal this act. For reference, I am from India and play in Mumbai server majorly. I never smurf, didn't even have an alt account before this act. Mid act, I find myself getting teammates who don't actually belong to diamond/plat rank. For example, I play cypher and my reyna and raze be like standing at the entrance shooting. I would be the one entering the site. I get that people in low rank bait for kills and duelists don't enter a site. But ffs, this is diamond I'm talking about. Controllers won't smoke or use utility like they are meant to and to top that off, their aim, my god their aim is no where near the ranks they are in. And this is not one game, these are some observations from multiple games. My mmr idk what level was it but i was getting +18 for a win and - 25 for a loss (+/- 1/2 based off performance). I dropped to gold 3 in a week. I kid you not, I have played tournaments with my team and went to semis by winning against diamonds and immortals. We actually scrim against immortal ranked players often and we all do just fine.

Finally, I made a new account. Try harded in unrated games and placement games to get silver 1. First game in silver, I won with 35 kills and got +38. I didn't even knew it was possible to get that much RR. I went on a winning streak for like 10 games or so and got to silver 3 within 2 days. I lost my first game in silver 3 and got -12 RR. I ranked to plat within a week and that's when I noticed something. Up until now, every second game I played, I had a teammate who was smurfing. Like 50% of the time me and one more teammate were smurfs and the enemy team was getting wrecked. 13-3,13-6,13-0 these were the final scorelines in silver and gold. As soon as I hit plat, first the increase in RR got to like +24 for win and -19 for a loss. The moment that happened, stressful games started where I picked reyna and dropped over 25-30 kills and still were losing. I was always entering and making space for my team to setup for plant and post plant, even when got the chance pushed up to CT for map control on attack and on defence, either got the first pick or looked for map control. To stop rushes, I was the only one recommended my team to use util and slow them for an easier retake where, I lead the attack too. All my comms and still we lost because someone didn't have mic, someone didn't even use their util or someone just had an silver level aim. While my opponents just were frying my whole team, including me sometimes. Still, got to plat 2 and in the rank up game for plat 3, I got a whole team of imm/diamond smurfs while my team where def plats who just got out of gold. It's after that I started to see some similarities -

1. If you're way lower than your mmr, you'll not only get high RR but the matchmaking will put you with people similar to your mmr in the same team so you can easily destroy the other team. I think this is done so that smurfs can rank up faster.

2. If you're on your mmr, you'll get a mixed bag of teammats, ngl, I didn't see any major observations here.

3. If you're at the verge of getting out of your rank at which your mmr is, that means you're gonna go above your mmr, the system will literally gatekeep you and put you in the opposite position I mentioned in point 1, you'll be the one facing smurfs, your teammates will be the ones who shouldn't be in the rank you're in and the system will try and kill 2 birds with one stone - rank up those smurfs faster and get you and your teammates to the rank your mmr dictates.

All that bs about rank system which the devs said is only good on paper. These are some things I've observered in soloq over 2 accounts and I've been playing since the launch of the game. The fact is your mmr doesn't change, no matter how hard you try, the mmr won't change because you won't win 15 games in a row in a practical scenario. Get yourself 3 friends who are immortal or diamond, 4 stack your way up to higher ranks. This is the only way and this is the reason for so many boosted players.

Riot - your ranked system is in the most shitty position it has ever been, soloq wouldn't let you rank up or increase your mmr and the 3-5 stack boosted players are ruining the game altogether.

Edit - another thing I forgot to mention was that if you spend more than 2-3 days ranking up and down a rank, say plat 2 to plat 1 and then again plat 2, the RR you get on winning will start getting lesser than the RR which will be deducted for a loss, for my case on my alt - in plat 2, I started getting +19/18 for a win and - 22/24 for a loss.