Capablanca was a very strong player but if he always played perfect and flawless chess he wouldn't have lost any games, and as it is he didn't only lose the match against Alekhine but had rather "human" results against some other Masters, for example 2 wins, 2 losses and 8 draws against Spielmann. Some GM's are much more critical of Capa than I ever would be though, GM Gormally writes:

"But what about Capa? How would he compare strength-wise to the players of today? I think he would come off rather badly. The difference in terms of knowledge and understanding between the players of today and the players of the 1920s and 30s is enormous."

http://www.pogonina.com/index.php?option=com_content&task=view&id=1183&Itemid=1

Carlsen can't have lost focus all that much though, he has performed 2815+ in all his nine latest tournaments. No other active player has ever been close to such a performance sequence.

I was wondering if Helltank could provide a reference. Petrosian often adopted ...Bb4-f8 in the Winawer. Notably 4. e5 b6 5. Qg4/5. a3 Bf8. The positions led to typical Nimzowitsch positions from 1. e4 Nc6 2. d4 d5, where black erects a cramped but solid game, with the intention of castling long and eventually preparing ...c7-c5 perhaps combined with ...f7-f5 and Ng8-h6-f7. Bronstein also utilised that build up on occasion.

Botvinnik, in that he played the Caro. Capa, as mentioned. Some possibles stylistically: Flohr, Seirawan, Nunn, Mecking.

But I also go along with those who point out the ferocious attacking side of Petrosian & Karpov (EG Karpov vs Korchnoi, the two most Key Yugoslav Attack wins of that century vs the Dragon), in addition to their fine positional skills; when they elected to pursue attack rather than some technical advantages.

Bf8!? is not at all rare in some lines of the Winawer. I'm not expert on the French Defense (or any other opening), but I've certainly seen it. And it fits perfectly with Petrosian's style.

The game Timman - Seirawan (1978) began 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 Qd7 5.Bd2 b6 6.Nf3 Bf8!? Seirawan explains: "An undeveloping move! With the move Bf8, what I've determined is that I want to keep my dark-squared Bishop, and in the future I want to be able to play c7-c5. and I don't want my Bishop to be trapped outside my pawn chain. I need the e7 square for a Knight, so the best square for the Bishop is f8." clear simple, grandmaster thinking.

Did you really think Petrosian was completely ignorant of opening principles? Or that he was just blundering?

I think Fischer was very similar to Karpov, both were very capable of winning due to seemingly 'minor' positional advantages.

Here's a very instructive game by Fischer where I sometimes get the impression that Black's game is pretty much lost due to 5...exf6?!, when White gets a longterm advantage (a pawn majority on the queenside):

So, when a player got a seemingly 'minor' positional disadvantage after a few moves in the opening, this could be sufficient for Fischer to win the game.

A similar example, a game which I admire a lot, by Karpov. Here after a few moves Black gets a 'bad' bishop, in the course of the game this 'bad' bishop gets even worse and it is amazing how Karpov finally realizes this advantage:

So again, both players, Karpov and Fischer, were really strong when they got a minor positional advantage in the opening, then they would play patiently and simplify the position to an endgame where they won.

Very similar in style. Also similar to Karpov, Petrosjan and Fischer - to some extent - is Smyslov, who was also very strong in winning due to seemingly 'minor' positional advantages. And of course Capablanca. The games of these masters are very instructive and beautiful in their very own way.

All the great players are universal players. They may have their individual preferences, but Petrosian could blow anyone off the board with a sacrificial combination if the position called for it, and Tal was more than capable of trading queens on move 10 and grinding home a positional advantage. Nobdy gets to that level without the whole package of skills.

Well , you have to consider the fact that Karpov played a more than Capablanca and so is more likely to make mistakes at some point. Also I was really referring to their style rather than the quality of their play ( and I do believe Karpov to be better than Capablanca)

Without taking anything away from Capablanca, it was a lot easier to play perfect chess in his day! If you look at his games, you will see many examples where his opponent accepted a weakness and then tried to defend that weakness. Capa then used his magnificent positional skills to mercilessly grind the opponent down. He brought a new level of positional skill to the game, and taught a generation of players the art of capitalizing on a weakness (see the games of Flohr and Fine for example).

Modern players will almost never resort to just trying to passively defend and survive--because they saw what happened to Capa's opponents! They counter attack, they sacrifice pawns or the exchange to get counterchances, in general, they do whatever they can to get active play.     This is the reason there are more "errors" in the games of modern champions, because the positions are more complicated and chaotic, not because they don't play as well as Capablanca. Many of Capa's opponents were content to defend passively and leave Capa alone to gradually exploit their weaknesses. The next generation learned from that, and what the learned is that passivity is death! So the play much more dynamic defense, And in more dynamic, complicated positions, there are more errors.

On the subject of Petrosian, I just got a copy of Volume III of Kasparov's "My Great Presecessors." This volume covers the reigns of Petrosian and Spassky, and contains detailed annotations of their games as well as a deep description of their styles and personalities. It's really a great book, and besides describing the two world champions, Kasparove devotes so time to some of their great contemporaries: Gligoric, Portisch, Leonid Stein, and Lev Polugaevsky. It's really a great book, and one of the best sources of deeply annotated Petrosian games.

As a teaser, here is Bobby Fischer on Tigran Petrosian: "Petrosian has the ability to see and eliminate danger 20 moves before it arises! I was staggered by Petrosian's ability, after achieving an excellent position, all the time to find manoeuvers that strengthened it." Sounds like a player worth studying.

Was Emanuel Lasker also a positional player like Anatoly Karpov?

@knowthyself

Lasker was very well versed in the positional ideas of Steinitz (his "Manual" was one of the first books to present those ideas to a general public) but as is famously known, he often applied more psychological considerations to his choice of moves in order to egg his opponent on into rash play, in line with his philosophical view of chess and life as struggle. Karpov is a positional purest in that he preferred the -- in his opinion -- best moves meeting the position before choosing a move based on any psychological considerations.