Struggling against Sidelines

I have this very weird situation where I am great against the Mainlines but struggle against the Sidelines. It's not really a problem when I'm White which I mainly the Queen's Gambit but it's been happening with 1.d4 d5 sidelines and and with the Taimanov Sicilian when they don't go for an immediate 3.d4. Is this a problem everyone else has or is it something that I'm doing wrong?

Yes, one of the main reasons chess is interesting is that you can't play the same moves against everything.

The other possibility is that what you are thinking of as the main line may be very different from what the actual main lines are.

Interesting how you brought up my games on the opening explorer. I play mostly on Lichess nowadays so it is not that accurate. I play the Slav instead of the Queen's Gambit Declined for example and that most of those games are when I was starting out. With regards to what I consider the mainline as Black is for the Taimanov, when they play 3.d4 going for the Classical Variation and for 1.d4 just getting a Queen's Gambit. 

Of course this doesn't mention all those other sidelines like the Bird which I currently struggle the most with

Yep, although I'd say the higher rated you become the less of an issue it gets, this is a problem for almost every player, especially online. A few generalized examples:

French players love their 3.Nc3 and 3.e5 closed centre positions and famously hate the open exchange variation

Sicilian players love to see the open Sicilian, and despise anti-sicilians like the Alapin etc.

1.e4 players are used to facing the Sicilian or 1...e5, but many complain about the tricky or annoying Alekhine, Modern, Scandi, or whatever.

King's indian players love the crazy Mar Del Plata classical mainlines but hate the boring exchange variation

That's just the way it works for most players. Luckily, the mainlines are (by definition) the ones we face most often. 

This is so far from the truth!

As a French player, my favorite line to face is the Exchange Variation as I simply don't lose to it in any decent time control.  Since 2014, I have 1 loss in the Exchange French across over 50 games with the Black side of it.  That one loss I was winning in severe time control in a very short time control (Game in 33 minues and 40 seconds, or 2020 seconds - The event was played New Year's Day of 2020).  All other games are draws or wins for Black, and yes, this includes facing players above me.

3.Nc3 is the hardest to defend and 3.e5 is next.

When a player knows the main line but not the side lines, it means that they were lazy in their opening study, memorized rather than actually studied it to UNDERSTAND what is going on, and if you were to STUDY rather than MEMORIZE, you would realize that the main line is the line you DO NOT want to face.

I quit playing the Sicilian because of 3.d4.  The anti-Sicilians are a joke.  People were beating me in the Najdorf and the Taimanov, not the Alapin or Smith-Moron Gambit (Mis-spelling is intentional!).

A book explains the main lines.  It is your job to interpret what is wrong with unsound sidelines.  It will give the main sidelines, like in the French, that would be the King's Indian Attack, Wing Gambit, and Reti Gambit.

But what about the following that I actually faced once?  1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Qb6 5.Ne2?  What is wrong with 5.Ne2 instead of 5.Nf3, which is the main line?

If you cannot answer that, then you don't understand the French Defense.  You memorized a few lines and can parrot those like a stupid bird, but you have no idea what to do otherwise.

WHY is 5.Nf3 the main line?  The Knight covers BOTH d4 AND e5.  From e2, the e5-pawn lacks the extra protection.

But, but, but, White has f2-f4.  Why not have the pawn guard it instead of the Knight?  Problem there is that it severely weakens the g1-a7 diagonal, often the King goes to g1, which then pins the d-pawn to the King, weakening the protection of e5, and White must also look out for tactics on d4.  For example, it may look like d4 is amply covered, but if Black attacks it 3 times, White guards it 3 times, and Black's Bishop can get to c5, then Black can take 3 times on d4, ending with White's Qxd4, just to face ...Bc5 and the Queen is pinned to the King.  So White typically does not want to play f2-f4 too early in the Advance Variation.

I applied all of these ideas to that game a good 3 or 4 years ago, and won easily.  It was literally -+ by move 15 to 20.

On the other hand, take the Seville Variation of the Grunfeld - 1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.e4 Nxc3 6.bxc3 c5 7.Bc4 Bg7 8.Ne2 O-O 9.Be3 Nc6 10.O-O Bg4 11.f3 Na5 12.Bxf7+ Rxf7 13.fxg4.

Sure, this is all fine and dandy.  Now what are you going to do when White or Black deviates?  Any idea?  The answer is NO in my case.  I don't truly UNDERSTAND the Grunfeld, and hence I do not play it from either side any more.  I don't know the sidelines.

The difference is, I acknowledge this issue, and specifically opt NOT to play the Grunfeld.  I can play a Dutch, King's Indian, Nimzo-Indian, Queen's Gambit Accepted, or Queen's Gambit Declined with Black as I UNDERSTAND those openings.  I mostly play the Dutch these days.

Others on here pick some random opening, like the Sicilian Dragon, and ace that, but then whine and complain about sidelines because they are TOO LAZY and LACK INTEREST in anything but the Dragon, and expect to be able to just mimic a dragon setup against anything.

You cannot play a main line without studying the territory that comes with it.  You want to play the Najdorf?  You better learn the Moscow, Alapin, Closed, Grand Prix, Smith-Moron Gambit, etc.

I play the Winawer, Classical, and McCutchen, but I also know the Exchange, Tarrasch, Advance, etc, and I understand why the Tarrasch and Exchange are such jokes and tend to equalize very quickly.  Facing 3.Nc3 is FAR more difficult.

You'll soon learn the "Main LIne" is what you truly do NOT want to face!

Thriller, not everyone plays to try to win all their games, but rather because they enjoy certain types of games. Openings are typically stereotyped through their mainlines, which means a person picking up an opening typically is attracted to the type of game they would get in the mainline.

When I play the sicilian, I want to get into a kalashnikov, because that is the type of game I enjoy. I do not enjoy playing against the closed or alapin, even though I can play against them perfectly fine.

I signed up to play the kalashnikov - I am unhappy playing against anything else. Especially rossolimo. 

In correspondence chess, or slow OTB games between titled players with time to prepare for the opponent, all of this is true, but these statements show a complete lack of understanding of the practical and physcological sides of chess. The 'hardest to defend' is whichever line white knows best. There is a reason why Dragon players score so well against the Yugoslav, but hate to see Anti-Sicilians, just like there is a reason why French Defense Sidelines like 3.exd5 and 3.Bd3 score so well for white at the amateur level. These are just facts, and even though there will always be exceptions like you who enjoy seeing sidelines, this is just how it works for the majority of players. 

If a Sicilian player faces the Open Sicilian 75% of the time then it makes sense to devote most of your study time there. The downside is that you are going to lose alot of hard games against specialists playing on their own turf. The Smith-Morra player only needs to study his Smith-Morra, so he is going to have a huge advantage in familiarity compared to the Sicilian player who needs to divide his study time between the Open Sicilian, Morra, Closed Sicilian, GPA, Alapin, etc. 

Even in my favourite opening, the Portugese, I checked the online games of David Smerdon (the hero of the Portugese) and as I expected, the line he scores worst against is not any of the critical main lines where white stands better objectively, but rather the boring and completely toothless 1.e4 d5 2.exd5 Nf6 3.Nc3

The idea that French players dislike the exchange variation is so well known in the chess world that you'd have to be living under a rock to be unaware of it. This applies all the way from beginners to several IM and GM authors on the French whom I've read.

I am well aware that you enjoy facing the exchange, but you exist in a very small minority of French players who feel this way. This is why I deliberately included the phrases 'most players', 'almost every player', etc.

Chess is funny when it comes to mainlines and side lines.

Against 1500-1900 players, I play mainlines English, Sicilian and EID but against a 2000+, he has the knowledge and experience with those mainlines so I switch to a reversed EID as white and as black, O’Kelly or Katalimov which scores well to begin with at the tilted level, but just weird looking for club players; like who goes c5, a6?

Somebody mentioned the Alapin, I’ll go Nf6 or d5 or dragon line, it depends on how inspired I feel that day. A plan is better than no plan.

End of the day, comes down to pattern recognition, tactics obviously and where the strengths and weaknesses are for both sides for the middle game.

Are you enjoying or achieving a playable middle game?

@1
"I am great against the Mainlines but struggle against the Sidelines."
++ What exactly do you mean with 'struggle'?
Do you mean you get worse results?
As long as you follow the trodden path of the main line you do not go wrong and you use no time. When you are forced off the main line you have to use time and think and you risk making a mistake.

No, I understand the psychological side of it.

In 2010, I beat an IM who played 1.b3.  He usually played 1.d4 against other IMs and GMs, but against experts and below, he figured going down the non-theoretical path would psychologically defeat his opponent.  He ran into a buzz saw with me and lost.

One could argue what I play as White is "psychological" via 1.b4.  It is perfectly sound, but does not give White the advantage that he may get with say, 1.d4.

But one thing beats psychology, and that is maturity!  Sure, in 1996, when my OTB rating was 1177 provisional, the Winawer was "more fun" than the exchange.  I would try to force action in the exchange, and often self-implode and kill myself (on the board, not literally).  That is why I use 2014 to today.  Pre-2013, 90% of my opening study would be main lines.  4.e5 in the Winawer (Virtually ignoring moves like 4.Ne2 or 4.a3), Open Sicilians, etc.

Then came 2013 and that year along with 2014, I quit complaining about opponents playing sidelines (I always did fine against Flank Openings, like the 1.b3 game in 2010 - it was sidelines of 1.d4 and 1.e4 openings that killed me), blaming my losses on "well, if they'd just play the right moves....", and simply did my homework, taking my knowledge in the main lines, studying the sidelines, and not just memorizing them, but understanding what specifically about them made them inferior.  WHY is 3.Nd2 inferior to 3.Nc3?  WHY is 3...c5 strong against 3.Nd2 and virtually a blunder against 3.Nc3?  Pre-2013, I played the Closed Tarrasch thinking defending that IQP was a problem.  Them I actually understood that White's main problem is the slowness.  The Knight Blocks the Bishop, which in turn Blocks the Rook.  Instead of closing the position with 3...Nf6, giving White time to maneuver his pieces to his liking, after 3.Nd2, it is best for Black to cut to the chase and go after White immediately.  The d5-pawn is relatively safe with a knight on d2, and it is not about the pawn, it is about the piece activity that Black achieves.

I did this across the board in a 2 year project as I had gone from French to Sicilian basically from 2010 to 2013, only playing the French sporadically during that stretch, so it really was just my main defense from 1996 to 2009 and 2014 to now.

I realized all of this when I noticed the same with the Sicilian in 2012.  I was winning all my anti-Sicilian games, and losing when White played 3.d4, suffering those crushes White gets with Nd5 and Nf5 sacrifices.

So sure I "know" the main lines and have known them for over 25 years when it comes to the French.  But the last 8 years, after "maturing" and putting in the effort with the sidelines, everything that I learned about the main lines clicked, and with that understanding rather than rote memory, it made non-main line light-years easier to face, and suddenly the main line has become the most difficult rather than the easiest to face, and it is not like the main line suddenly had reputations found for White.  It was all about maturity and putting in the effort.

Without this "effort", yes, all you are going to succeed with is the main line.  You are excited about one line, and just jump on the bandwagon.  It is like being a Dallas Cowboys fan when they are really good, never having followed them when they were bad, and refusing to follow the other 31 teams.  I have been a Giants fan since 1983, whether good or bad, and also follow the other 31 teams, which is why I succeed so well in fantasy football, and no, I do not draft a bunch of Giants.  I only take a Giant when that is the best player available!

So yes, psychology can win you chess games, but those with maturity beats those that use psychology, and those too lazy to do what I did in 2013 and 2014 will be defeated by psychology.  Those with maturity will have very few problems with those opponents, and will find the main lines the hardest to face!  Instead of scoring 48 percent with Black in the main lines and 30 percent against sidelines, you will see yourself scoring 70 percent against the sidelines and the same 48 percent against the main lines.  It is not that the main lines suddenly become tougher.  It is that the sidelines become vastly easier to face while your results against the main lines remain the same!

A 2100 player that plays 1.e4 as White exclusively learned this the hard way against me.  Now, instead of lines like 1.e4 e6 2.d4 r5 3.e5 c5 4.c3 Qb6 5.Ne2 (He always liked 4...Nc6 5.Be3 against French players, which is why I tell those that play the 5...Qb6 line to play 4...Qb6 and 5...Nc6), he knows he has to go into the main lines, and while I beat him the last time I had Black, he won the previous one in a 6.Be3 MacCutchen.

Psychology only works against you if you let it (usually through laziness and showing obvious signs of disinterest in side lines)!  Maturity kills psychology.  I won't lie, sidelines got the best of me from 1996 to 2012.  NOT ANY MORE!  (Talking serious competition over the board.  Anything, including 1.f3, can win in 3 minute online blitz.)

as i don't get position, unorthodox replies confuse me into suicide by pawns.

surprise openings get almost everyone though. i've beaten high rated players with unsound lines many times. when people don't see the "right move" OTB, they stumble. that's why I created the zeller ice queen thread. it's an "unsound" alternative to the f3 main line, but performs close to 60:30 under 2000. 

1.e4 d5 2.d4!? Bf5 3.Qe2!? people just don't see the best line AT ALL, but there's a lot of mates in under 10. i'd say that falls under everybody territory.