What common things make weaker players weaker in your experience?

I see no one gave any sort of answer or in the format I was asking except one person by direct message. Seems it's a waste of time posting anything serious.

Generally, when they make mistakes. More mistakes are made when players fail to play within their capabilities. And that is the correct answer to your question.

After all, if a weaker player plays ultra aggressively, I may possibly blunder and fail to prevent the attack but I'm more likely to spot the weakness and punish it. But if a weaker player plays very carefully in a principled manner, I'm the one who has to try something to win. The odds I get it wrong aren't enormous but they're higher than me blundering when an opponent makes an incorrect attack.

I'm ~FIDE 1400. I am commenting on players around 1000-1150 FIDE. In India, these players are usually quite strong. They play good moves and all, till the time they see thay their opponent is playing *normal* moves. As soon as you play an unorthodox move, they stumble and start making errors. In a recent tournament, my 1120 FIDE opponent was outplaying me and we entered the late middlegame with a good advantage for my opponent. Then, as soon as I played unorthodox moves like Kh8, g5, h5, etc., even after he had played f4 before this, he started making errors. Grave errors. He allowed me to enter an endgame with a definite edge for me, which I converted.

Too much talk

Like GOP says maybe not so useful, but here are some thoughts that come to mind.

Generally I'd say the stronger a player is the more tension they can handle.

There was a joke among some masters at a club I used to visit that no player U2200 could resist relieving pawn tension (leaving two pawns attacking eachother) for as many as 3 moves.

Along with captures I'd say the lower the rating the less aware they are of all the transitions. As an easy example lets say we have a R+R+N vs R+R+B position. Lower rated players are likely to rush to one of the endgames (rook or minor piece). Stronger players may trade only one set and play for a while in the R+B vs R+N, and even stronger players (if it's useful for the position) may not trade at all.

Another. I think the lower the rating the less aware they are of practical chances. Especially new players will only think what the engine tells them (I don't blame them) but eventually you realize 0.00 may be extremely far from a draw, and 2.00 may be drawish. It just depends.

So accordingly you choose your opening and middlegame play from this.

For example it's common to hear a low rated player want to avoid the 4 knights, or a d3 Ruy because it's "boring" and "drawish" but a strong player will happily give you 0.00 on move 15 in a complex position because in practical play there's a lot of potential to outplay your opponent.

Another. The stronger the player the more they'll fight in the endgame. Plenty of times I've had a "drawn" endgame against a 2200+ OTB, but I get outplayed and lose. Plenty of times I've had a "drawn" endgame against 1800 players OTB but I win...

And some of them really are "dead" draws, but you find ways to force accuracy, and then wait for them to be inaccurate.

There are also ways to use the clock.

I'm probably still a novice at this stuff, but one game that comes to mind is a game where I screwed up, and now I'm faced with a middlegame where my opponent has all the play, and it's a big kingside push against my king

So a "normal" reaction is to find some desperate counterplay somewhere else. Rush out a pawn break even if it's a sac, and try to make a mess.

But I decided the problem was there was too much time on the clocks. Either way I was lost, so I decided not to go for desperate play until my opponent had less time. I curled up into a little passive ball on the kingside and let him burn time. Then I saced a piece in the center to make a big mess... and I ended up winning.

Maybe a casual observer would think I was an idiot and got lucky, and in some sense that's true, but there are a lot of practical decisions like this... and of course you can also use this when winning. If you're in control of all the play in a position, sometimes it's useful to alternate a lot of threats but never execute them. Then after your opponent burns time you can initiate the critical position(s).

Haha, I guess so.

It's like after they both decline once, they both decide to never calculate it again

Leaving aside the lack of precision due to bad form, which can happen at any level, the question should be if the player understands what's happening and if he's capable of playing accordingly, thus establishing the sources and not the consequences.

On the way around, trying to categorize the mistakes according to the current competitive strength of a player can be deceptive. For instance, a number of players work on pattern recognition on some systems and become pretty good at them, but when taken from familiar waters they don't know what to do. Others are talented but lack the time or disposition to work hard. Then the same sort of "mistakes" can happen at different levels and for very different reasons.

Players rated below 1000 don't check whether their pieces are hanging before they make moves. Even players as good as 1400 have the temptation to play empty one move attacking moves which can easily be paired. I am talking about chess.com ratings, I am rated 1911 rapid, 1853 blitz as of the time of writing this comment.

I follow you on quora, I like your analyses and responses there.

Thanks

Just at the end there you mentioned 160+. Did you mean 1600+ or were you talking about ECF (formerly BCF) grades where 160 is about equivalent to 1880 FIDE? Higher than that in the North of England, where we always tended to be under-rated compared with the South and the Midlands, even after we all got 10 measly points added to our grades. But that was why Lancashire was continually winning National County Championships or being runner up to Yorkshire. I played more or less top board for Lancashire U150s and then I think it was U160s and again, subject to fluctuations, near top board when my rating wasn't over the limit. I preferred not to play for the U180s because I would be near the bottom of the board order and playing a low-rated person, whom another county had scraped up because they were short of players. So what with that and tournaments and local leagues I'm sure I played over 2000 rated games, in my 25 years of high activity.

Converting to Chess.com tatings, under 1600s can often play a very good game but they are lacking something. That something can be accuracy, imagination or concentration. Three different things but all are necessary. So under 1600s tend to make mistakes caused by one of those things.

Getting a bit higher, under 1800s FIDE usually play more solidly and creatively. You have to really pressurise them and they will crack. At my best I would expect to beat an 1800 all the time, at slowplay. As you get a little better, around my standard, people playing with a high degree of confidence sometimes make errors and they aren't used to playing people who will spot the error and capitalise. When you're playing people around 180 ECF, which is 1950 FIDE, they play often with a strong degree of confidence and put in a lot of thought, very often, but they can miss things. I didn't normally play anyone over 220 ECF, except for the very occasional chess master on top board for another local team. 220 ECF is about 2350 FIDE.

The last game I ever played competitively was against such a 2350 FIDE. I "should" have won with black. He tricked me beautifully: something I would have been proud of, if I'd done it. Stared at his position for ages. He was completelly lost but he came up with a beautiful swindle. I was very short of time and with five minutes more would have won. But I fell for it. Should have offered a draw. He told me afterwards it had been his most difficult game all year. So I cracked under the combined pressure of time and unexpected tactical problems. Something I usually used to do to others.

I am a weak player myself at 200 something in rapid

Blunders happen all the time. 

Some players fall for the Scholar's mate, including myself many times until i learnt how to defend it and do it myself. 

People would often sacrifice a bishop for a knight, sometimes even castle for knight.

Body language can give away a LOT, especially with newer players.

Saying a position is a draw, when it is a draw, and offering a draw, when there is still play left in the board.

Yes I often try to win drawn games and to win or draw lost ones.

Assumptive thinking and failing to search for counter-play to their ideas.

First, trading everything,one mover (only cares about that one move, don't calculate the problems that can come with it,and last not enough knowledge on puzzles, matting patterns, openings , middle game and end game

Moving impulsively, without considering the opponent's likely replies.

Attempting to attack with one or two pieces, instead of developing more pieces first.

Ruining their own position (especially their Pawn structure) with a series of one-move threats that come to nothing.

They rely too much on calculation and not much on general principles, a strong player can play a reasonably good game without calculation just relying on principles of solid positional play , weak players calculate too much , mostly inferior risky moves which an experienced players rejects without even considering, thats one thing weaker players should try and cure , a good filter in move selection