Why does black have an advantage here?

Question

I am studying now old Polish book "ABC Szachisty" ("ABC for Chess Player", informal translation) and the following example is given there:

[FEN ""]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. Nf3 e5
5. d3 Bg4 6. Bd2 Nc6 7. Qe2 Nd4 8. Qxe5+ Qxe5+
9. Nxe5 Nxc2# 

And this example is aimed to show the significance of the center. So my two questions that I don't understand here are:

1. Why this example satisfy its aim, i.e. shows how important the center is? My guess would be that since black figures are well centralised, they have short distance to white's position, and that is what is making mating attack possible (also white's mistake of taking the pawn). I don't understand however why control over the center is important here.

2. Why, after 6th move black has better control over the center?

[FEN "r3kbnr/ppp2ppp/2n5/q3p3/6b1/2NP1N2/PPPB1PPP/R2QKB1R w KQkq - 3 7"]

I see that white knight on f3 is pinned and f1 bishop is blocked. Also, white game is very passive here. However, black has only two minor pieces mobilised here and whole queen's side is not active.

Answer 1

Answering the second question first,

"2.Why, after 6th move black has better control over the center?"

Black's pawn on e5 is better than white's pawn on d3. Both sides have traded a central pawn. Black's e-pawn occupies a central square and controls another. White only controls e4. It's about the pawns. Pieces can move around and control various squares. Notice every major opening spends the first 2-3 moves establishing the pawn structure in the center. I know that can seem confusing because hypermodern openings appear not to do that but they actually do. They just do it in a more subtle way. My advice is just to focus on understanding classical centers until you get around 1900 then the hypermodern openings will make a lot more sense. Focus on the pawn structure in the center and think of the pieces as support pieces for the pawns.

"Why this example satisfy its aim" It's not a great example. But, you can see that black is able to more actively develop his pieces. For example, black's light square bishop is able to get out and pin the knight but also has f5, e6 and d7 as options. The white light squared bishop only has one legal move (e2) and it's pretty passive. Black has a free and easy development with lots of choices on where to place his pieces while white has few choices and his pieces are tripping over each other and fighting for the same squares (e2 for example)

"Why does black have an advantage here?" After move 6, black has a better center. Development is equal. Black is one move away from castling while white is two. That's how you evaluate opening positions- center, development, king safety. Black is better in two areas and equal in the third. Therefore, black is better.

Answer 2

First things first, this is an example of a very poorly played game, so Black gained its edge because of White's tactical mistakes, rather than by taking advantage of their extra space. This is a "fault" often made by chess authors when trying to illustrate a concept. They will explain the events in a game in a way that "fits their narrative" rather than provide an objective analysis, which is this case would lead to conclude that the position is pretty much balanced if not slightly advantageous for White until the horrible 7.Qe2.

It is true, though, that by move 6, White's lack of interest in fighting for the center costed them most of its starting advantage despite Black having lost several tempi with their queen. White could have played 7.Be2 (among others) and still have a reasonable position despite Black's lead in the center due to their extra development.

Answer 3

Black has more space. The e5-pawn gives Black four rows to move around in, while the d3=pawn gives White three (and the 4th rank is kind of a no-man's-land). That extra board room confers ease of the development: no problems for black bishops, while White's Be2 isn't so happy.

Later, the space advantage gives Black a chance to grow with ...f7-f5 plus ...e5-e4, while White hasn't the same. White's job will be trying to gain equality in the center with d3-d4 or f2-f4.

This position is a good example of why center control is our main positional goal early in the game.