user1105: I recently asked this question: Why Anand and Carlsen insisted on playing the same opening/defense
FM Rauan Sagit answered: 

In my view, in terms of opening preparation, the Anand team failed to
  obtain middle game positions that suited Anand's style. In general, I
  think that Anand should have aimed for long middlegames with most
  pieces intact. While Carlsen should have aimed for long endgames with
  most pieces exchanged off the board. From this point of view, Carlsen
  got his types of positions, while Anand failed to get his. This can
  partially be explained by the chosen opening systems. Additionally, I
  think that Anand should not have willingly exchanged queens in a
  single game.

That got me thinking, when a strong endgame player faces a strong middlegame player, does the latter stand a chance?
The endgame player would force the opponent into exchanging pieces and there's nothing you can do about it simply because he doesn't care about his pieces, just like what happened in the championship match,  am I right? What are the odds of a middlegame player defeating an endgame player?

user1943: I think it would be wrong to say that Carlsen as a middle game player is weaker than Anand. Carlsen is a quite strong middle game player, and the reason why he was eager to play end games was that he was getting minor advantage for his pieces in the middle games. He is the strongest player in the world, and having almost 100 points difference before the match was the indicator of the difference between Carlsen and Anand.

user3872: I would say that a strong middle game player would understand the middle game enough to know that the particular stage sets up the middle game. For example, simple things like pawn islands, doubled up pawns, bishops, pawn structure, and backward pawns are things that good middle game players will look for. Thus, even if the good endgame player gets the game to the endgame, the middle game player would already have an advantage. Seems to me that the middle game player has considerable better chances.

user657: "What are the odds of a middle game player defeating an endgame player?"
Well, given the Kasparov-Karpov match history, I'd say, "Pretty Good!"
Seriously, the answer is less about phases of the game and more about the players themselves. The "endgame player" has to be able to survive the best shots of the "middlegame player" before the endgame even arrives.
In the case of Anand-Carlsen, I really don't think second-guessing Anand's match preparation means anything. From where I sat, Carlsen would have won, no matter Anand's preparation. He's simply the better player, and while short matches like the current WC events allow greater probability for randomness to elevate the lesser player, it wasn't enough to save Anand.
Just like Fischer wasn't going to be beaten by any of his elders, and Karpov, and Kasparov, Carlsen is going to sit in that seat until one of his generation, or the next, rises up (Caruana, perhaps?) to unseat him.

user1856: Anand's problem was mainly psychological. Anand is a world class endgame player, but he made some careless mistakes.
You can't really be considered a strong middlegame player if you have no endgame concept. Recognizing favorable endgames while calculating variations in the middlegame is part of being a strong middlegame player. But perhaps some players don't know how to proceed once they transition to that endgame? If that's the case, I would favor the stronger endgame player to win.
Obviously endgame skill is more valuable to have, it serves as the backbone for the opening and middlegame. Imagine a so-called "Strong" middlegame player who knows how to exchange into a favorable endgame, but has no confidence in his endgame skills?

user2001: My point was that Anand could prevail in dynamic middlegame positions, while Carlsen could prevail in endgames with a minimal advantage. Of course, Carlsen masters all three phases of the game on a top level. At the same time, sharp and complex middlegame positions release more adrenaline and require more focus. Regarding comparing a middlegame expert and an endgame expert, it is not so easy to exchange pieces. An exchange of pieces is a mutual decision and it takes two to tango. One way of keeping most of the pieces on the board is to select opening systems accordingly. For instance, you can choose the Volga gambit
[FEN ""]
1.d4 Nf6 2.c4 c5 3.d5 b5

and most of the pieces will be on the board for a good while. In some systems, it is easier for the endgame expert to steer the game towards e.g. an early exchange of queens. While in other systems, it is much more difficult to steer towards multiple exchanges. That being said, all the professionals are experts in all three phases of the game. So the key is to steer towards positions where they risk the most and therefore create the situation they prefer to avoid.

1105: <p>I recently asked this question: <a href="https://chess.stackexchange.com/questions/4155/why-anand-and-carlsen-insisted-on-playing-the-same-opening-defense">Why Anand and Carlsen insisted on playing the same opening/defense</a></p>

<p><strong>FM Rauan Sagit</strong> answered: </p>

<blockquote>
  <p>In my view, in terms of opening preparation, the Anand team failed to
  obtain middle game positions that suited Anand's style. In general, I
  think that Anand should have aimed for long middlegames with most
  pieces intact. While Carlsen should have aimed for long endgames with
  most pieces exchanged off the board. From this point of view, Carlsen
  got his types of positions, while Anand failed to get his. This can
  partially be explained by the chosen opening systems. Additionally, I
  think that Anand should not have willingly exchanged queens in a
  single game.</p>
</blockquote>

<p>That got me thinking, when a strong endgame player faces a strong middlegame player, does the latter stand a chance?</p>

<p>The endgame player would force the opponent into exchanging pieces and there's nothing you can do about it simply because he doesn't care about his pieces, just like what happened in the championship match,  am I right? What are the odds of a middlegame player defeating an endgame player?</p>
 1943: <p>I think it would be wrong to say that Carlsen as a middle game player is weaker than Anand. Carlsen is a quite strong middle game player, and the reason why he was eager to play end games was that he was getting minor advantage for his pieces in the middle games. He is the strongest player in the world, and having almost 100 points difference before the match was the indicator of the difference between Carlsen and Anand.</p>
 3872: <p>I would say that a strong middle game player would understand the middle game enough to know that the particular stage sets up the middle game. For example, simple things like pawn islands, doubled up pawns, bishops, pawn structure, and backward pawns are things that good middle game players will look for. Thus, even if the good endgame player gets the game to the endgame, the middle game player would already have an advantage. Seems to me that the middle game player has considerable better chances.</p>
 657: <p>"What are the odds of a middle game player defeating an endgame player?"</p>

<p>Well, given the Kasparov-Karpov match history, I'd say, "Pretty Good!"</p>

<p>Seriously, the answer is less about phases of the game and more about the players themselves. The "endgame player" has to be able to survive the best shots of the "middlegame player" before the endgame even arrives.</p>

<p>In the case of Anand-Carlsen, I really don't think second-guessing Anand's match preparation means anything. From where I sat, Carlsen would have won, no matter Anand's preparation. He's simply the better player, and while short matches like the current WC events allow greater probability for randomness to elevate the lesser player, it wasn't enough to save Anand.</p>

<p>Just like Fischer wasn't going to be beaten by any of his elders, and Karpov, and Kasparov, Carlsen is going to sit in that seat until one of his generation, or the next, rises up (Caruana, perhaps?) to unseat him.</p>
 1856: <p>Anand's problem was mainly psychological. Anand is a world class endgame player, but he made some careless mistakes.</p>

<p>You can't really be considered a strong middlegame player if you have no endgame concept. Recognizing favorable endgames while calculating variations in the middlegame is part of being a strong middlegame player. But perhaps some players don't know how to proceed once they transition to that endgame? If that's the case, I would favor the stronger endgame player to win.</p>

<p>Obviously endgame skill is more valuable to have, it serves as the backbone for the opening and middlegame. Imagine a so-called "Strong" middlegame player who knows how to exchange into a favorable endgame, but has no confidence in his endgame skills?</p>
 2001: <p>My point was that Anand could prevail in dynamic middlegame positions, while Carlsen could prevail in endgames with a minimal advantage. Of course, Carlsen masters all three phases of the game on a top level. At the same time, sharp and complex middlegame positions release more adrenaline and require more focus. Regarding comparing a middlegame expert and an endgame expert, it is not so easy to exchange pieces. An exchange of pieces is a mutual decision and it takes two to tango. One way of keeping most of the pieces on the board is to select opening systems accordingly. For instance, you can choose the Volga gambit</p>

<pre><code>[FEN ""]
1.d4 Nf6 2.c4 c5 3.d5 b5
</code></pre>

<p>and most of the pieces will be on the board for a good while. In some systems, it is easier for the endgame expert to steer the game towards e.g. an early exchange of queens. While in other systems, it is much more difficult to steer towards multiple exchanges. That being said, all the professionals are experts in all three phases of the game. So the key is to steer towards positions where they risk the most and therefore create the situation they prefer to avoid.</p>
