For example:
A 1300 and 1200 rated player have a game. The game is roughly equal throughout the opening and middle game, but towards the end, the 1300 rated player obtains and advantage of one pawn through a tactical shot, and wins the endgame. Though the difference is 100 points, the game was equal for the most part. It was a minor difference that made the difference between a 1300 and a 1200.
Another example:
A 1700 and 1800 rated player have a game. The 1700 had studied deep opening theory and comes out of the opening and middle game with a slight advantage. The 1800, however has studied endgames and positional play, regaining the losing position, and winning the game eventually.
Positional play is basically understanding what each piece should be doing, and where it belongs. A bishop blocked by its own pawns is considered “bad”. A knight on the 6th rank is considered to be a strong knight. A hole created by a lack of pawns is a weakness. Knowing how to target these weaknesses, and prevent them from happening to you, is positional play.
“I heard someone say they can win tactically and lose positionally, or something like that, and beat people many hundreds of ELO points above them in poor positions.”
That’s pretty much a myth. Younger individuals only tend to have an avebatage in learning chess because their minds are still undergoing development. Children also typically have more time on their hands than adults.
The elo system isn’t inaccurate, but it is inflated compared to Fide ratings. It’s estimated that a 2000 online player is between 1600-1800 OTB.
Hope I answered your question.
I have heard people say that ELO rating starts to lose accuracy under two conditions that I have no idea about.
1) Extremes of ELO. I often see FM's and GM's still competing against each other. I thought, theoretically, if you're 200 ELO points or more above someone, then it really shouldn't even be much of a contest, but 2400-2500s are COMPETING against 2700-2800s. I also saw Nepo and Magnus very close, almost tied, in performance at some very famous thing, round 6 being the most prominent and longest game that is discussed in depth. Magnus was many points more in ELO than Nepo. And also, they say the very worst players should beat each other despite being a few hundred points above the other. This sort of thing does not fly with tennis pros, and I know many tennis players who would easily beat and not even play with people a level below them.
2) Youth players. Somehow, their brains are different, and I heard someone say they can win tactically and lose positionally, or something like that, and beat people many hundreds of ELO points above them in poor positions. I don't even know the difference between tactical or positional. Could someone clarify why youth players' ELO ratings are not accurate?
What is the rate of development that makes some GM in their mid-20s lose a hundred ELO points from when they were in their early 20s? Apparently, tennis pros in the earlier times used to retire at age 27. Why are the current best chess players in this world in their late 20s or early 30s? What age do people actually stop becoming the best and lose brain/motor/physical functioning? I read age 24 or so is when reflexes slow down, so that is why I don't understand why we have an age 31 Magnus Carlsen dominating this world.
3) Tighter time controls. I just don't understand how IMs have a much more even playing field in tighter times with GMs. Even much lower rated has more chances to win. I also saw some YouTube video of Hikaru climbing to 3500 ELO, so that theoretically means he should beat Alphazero, or at least dominate 2800s Magnus. Yet, Magnus beats Hikaru, even in blitz, and no one gives serious conversation about bullet or rapid in discussing who the best chess player is. What is going on with this weird rating system? I'm not seeing too much accurate information about blitz ratings when I look it up. I see 3379 as a bullet record from Magnus, but no one ever discusses Hikaru's 3500??? I would NEVER have known or heard about Hikaru's 3500 ELO if I don't follow him on YouTube, but when I look that impressive ELO up elsewhere, I don't see that info. What am I not understanding?
https://lichess.org/@/Kingscrusher-YouTube/blog/magnus-carlsen-creates-new-all-time-bullet-rating-record-11th-november-2021/kTiFcikR#:~:text=Magnus%20Carlsen%20creates%20new%20all%20time%20Bullet%20rating%20record%20%2D%2011th%20November%202021,-CM%20Kingscrusher%2DYouTube&text=Recently%20Magnus%20Carlsen%20had%20a,all%2Dtime%20Lichess%20bullet%20record!
Apparently, GLICKO or some version of it is used by Lichess and is supposed to be more accurate, but I'm sorta understanding that ratings are more inflated? I'm confused.