Two opening repertoires: one against much stronger opponents, and one against much weaker opponents

If you look at the Elo rating distribution graph, the mean is 1640, and most importantly the standard deviation is 340. What this means is that, if you were an average player (1640 Elo), and if you played against a completely random player, there would be 16% chance that he is much stronger than you (defined as rated more than 340 Elo above you) and 16% chance that he is much weaker than you. And in reality, the probability that he is much weaker than you is much bigger than 16%, because most weak chess players don't have an official FIDE rating.

I had an idea: build two opening repertoires, one good against much stronger opponents, and one good against much weaker opponents.

So two questions:
- Which kinds of openings are good against much stronger opponents?
- Which kinds of openings are good against much weaker opponents?

Mainlines or sidelines?
Open or closed?
Tactical or positional?
Sharp or slow?
Chaotic or quiet?
Theory-heavy or theory-light?

When playing against much weaker opponents, an opening can be good either because it maximizes your winning probability (or more precisely the winning probability plus half of the drawing probability) or because it allows you to relax and play on autopilot without needing to focus intensely.

Against much weaker opponents, Black should probably not play the French and the Slav, because this would allow White to play the drawish Exchange variations, and a draw would be a bad result for the much stronger player (though of course still not as bad as a loss).

What about the London + Caro-Kann + Slav with ...Bf5, a system which I currently play, is this system good against stronger or weaker opponents?

Against "much weaker" opponents it actually shouldn't matter what openings or defenses you play - you should be able to win with relative ease, regardless.

Regarding repertoires - for me, instead of thinking of a repertoire for "weaker" or "stronger" opponents - I just have a main repertoire, and a back-up repertoire, based on style of play.

For example, my main OTB repertoire is more on the hypermodern end. My backup repertoire is more on the classical end. Different choices for different flavors of game ...

Just some food for thought.

indeed. I think you have a very cool mindset. Developing your own Chess Philosophy does involve thinking about things such as this, especially if you love playing chess whether for sport or just casually. For me, in my early years I can admit I tried to hone my Opening Repertoire for myself~regardless of the Status of my opponent: Experience, Rating, Observed Playing Style and other stuff as well. When you reach a certain level though; yeah one does sometimes use perceived "weaker" stuff, an opening you've never played before: either one you've always disdained or one you've always admired, and probably one (you've been studying low-key) just to unveil for surprise value because of your particular opponent, on this certain day.

Another benefit to having more than one opening repertoire is the simple fact that a wider range of openings will give you exposure to a wider range of middle-game positions and a broader spectrum of middle-game plans... not to mention, greater variety in the endgames.

All of this is GOOD for your overall development as a chess player.

Against stronger opponents? Choose lines that are tactically active, that require constant alertness and constant focus, but which are considered to be positionally SOUND.

Many years ago, in 1988, I had a chance to play Mikhail Tal, then ranked 4th in the world. Since it was part of a simultaneous display, I had the Black pieces. What do you suppose I decided to play against Tal's 1. e4 opening move?

Personally, I liked to play the Sicilian Najdorf as Black, but of course Tal had decades of tremendous experience as White against the Najdorf versus Grandmaster opposition (crushing Bobby Fischer himself two or three times in a row in that line, for instance).

If I'm gonna play somebody rated 800 or so points higher than me, I need an opening that is tactically sharp but strategically sound.

I played the Najdorf. I drew.

Namely because, you have reached a point in your Chess Life (played numerous tourneys, club games, online stuff etc) that you simply can do it. But not necessarily that you should do it, mind you heh. Of course, developing your basic skillsets, fundamental practices (positional awareness & complimentary tactics) rudimentary endgame knowledge, practical study etc etc are the things that should go alongside with any chessic decision come game time.

Well, you should still definitely know to play scholar's mate against a 100-200. After that is personal preference...

indeed. @blueemu (#5) Of course, I totally agree with his points.

Point I should make also, these days methinks having online presence on multiple chess sites it is easier for players to have multiple profiles ie totally different prepared repertoires, on each different or even on one site! Otherwise, back in my days (unless you were going incognito for um varying circumstances heh) it was just simply Adding to your already Prestigous Opening Repertoire!

I generally play the same openings, so it doesn’t matter if my opponents are stronger or weaker because most of my games are decided by missed tactics, blunders and end game techniques.

With that said, I do prefer open and tactical games. For some reason that I cannot explain, I run into closed positions and anti-Sicilians more often at the 1600-2000 bracket.

(My responses in bold above)

Interesting idea 🤔

@KeSetoKaiba

It's all relative. The mean depends on the pool of players. The mean on chess.com (660) is much much smaller than for FIDE Blitz (1640). For the subject under discussion in this thread, what the mean is does not matter, whether it is 660 or 1630 doesn't make any difference, only the standard deviation matters. And the standard deviation varies much much less than the mean. The standard deviation is always somewhere between 300 and 400. The point is just that there is a large fraction (16%+) of players who are much stronger and much weaker than you, so it makes sense to have a repertoire specifically designed to deal with them.

Misevaluating your opponent can happen, but it happens only very rarely. You can almost always see someone's rating, and someone's rating is almost always accurate. When you play the same opponent IRL multiple times, it is possible to misevaluate him the first time, but after that you'll know for certain how strong he is so it will no longer be possible to misevaluate him.

If you pick the wrong repertoire, it won't be anywhere near as catastrophic as you described ("getting crushed"), it won't matter very much, it's just that your expected average playing strength during this game will be 50 to 100 Elo less than if you had picked the right repertoire.

True, regardless of what opening you play, against a much stronger player you will lose over 95% of the time, and against a much weaker player you will win over 95% of the time. But perhaps the idea of having two repertoires will increase your winning probability against much stronger players from 1% to 2% and decrease your losing probability against much weaker players from 2% to 1%. A 1% change would usually be completely insignificant, but here it is not. Whether your winning probability is 50% or 51% makes no difference, the difference is only 7 Elo. But whether your winning probability is 1% or 2% makes a huge difference, a 120 Elo difference.

FIDE is of course a tougher player pool because anyone willing to spend on more expensive memberships and travel costs internationally are probably better chess players in ability (on average). If you say, "For the subject under discussion in this thread, what the mean is does not matter, whether it is 660 or 1630 doesn't make any difference, only the standard deviation matters" then I'd still stand by the fact that your thought-process seems to over-value openings.

In practical play, the games are decided out of the opening much less frequently than other areas of the chess game and other concepts. Your time is better spent learning those with the time you would save by not investing into creating two repertoires.

The opening stage of the game is the most forgiving because there is still a lot of chess left to play. The best you can hope for in most openings is to gain a small advantage such as half a pawn in engine evaluation. Edges like this likely mean little when the rest of the game doesn't have precision all the way to converting that edge into a win (if a win exists; principle of two weaknesses etc.).

It isn't that opening study is useless, or that building an opening repertoire is a bad thing. Having opening knowledge and concepts you've studied are of course better than not having this knowledge at all. It is just that your time is likely better spent elsewhere, unless you really enjoy openings. In that case, have fun with whatever you like, but recognize that you may not be utilizing your chess improvement time optimally.