The 9...a5 Move Against the Bayonet Attack: A Strategic Pitch Without Verified Data

In the file I received, the headline spoke of European schools chess champions and a cultural festival in Tsaghkadzor. The body, line by line, spoke of a DVD on the King's Indian Defence, advising Black to answer the Bayonet Attack with 9...a5. Two subjects, one document, and not a single line joining them. For a data journalist, that is the clearest anomaly of the week. People call it a shock; I call it data that has not been read. Here, the unread data sits inside the structure of the source itself. I separate the two halves, analyse only the half with self-standing evidence, which is the opening material, and mark the rest as a headline fragment with nothing beneath it, rather than filling the gap with guesswork. The King's Indian Defence is a classic hypermodern system. Black concedes the centre, builds the Bg7, d6, e5 wall, then counterattacks. The line in question is the Mar del Plata with 7...Nc6, where both sides race to storm opposite wings: White against the queenside, Black against the king. The basic move order: 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5 7.0-0 Nc6 8.d5 Ne7. White's Bayonet Attack, 9.b4, pushes the b-pawn to gain queenside space and disrupt Black's usual c6 or c5 plan. The move is not new. It has appeared steadily at elite level since the late 1990s and has become one of the most uncomfortable tests for the Black player. Black's mainstream reply is 9...Nh5: accept an open position, steer into forcing, concrete lines, the kind of chess engines handle most comfortably. The product I am looking at proposes a different direction: 9...a5, a queenside space-gaining move that hits the b4-pawn and prepares c5 or Be6. That is the selling point. Rather than plunging into forcing lines, 9...a5 aims at strategic positions with few concrete variations, suited to a player who wants to understand plans rather than memorise moves. The argument sounds reasonable. The trouble is that it has not been verified. When I examined the technical section, the data table was almost entirely empty. No engine match rate. No ACPL. No win rate, no draw rate, no sample of games. No author named. No player named. All that exists is prose: 9...a5 is presented as the antidote to the Bayonet, leading to positions computers often do not know how to handle. That is an assertion. Evidence is absent. Across 37 years of watching this industry, I have learned one thing. The opening market is where people pay for variables nobody has verified. An opening product sells on the author's reputation and on a promise of practical points, not on published validation data. That does not make the product wrong. It only means the buyer is paying for a hypothesis, not a conclusion. Three pillars support any serious opening assessment: engine match rate, ACPL, and the actual scoring rate in a database across rating bands. All three are missing. The claim that 9...a5 is better than, or equal to, 9...Nh5 in theoretical terms therefore cannot be verified from this document. It can only be judged as a deliberate practical choice. And that practical choice has its own logic. 9...a5 was not invented from nothing. It has appeared in top-level practice as a space-gaining, tempo-gaining move preparing c5. Its value lies not in overturning theory but in shifting the game away from the area an opponent has prepared most thoroughly. A move does not need to be fast if it reads the maze before the audience sees it. This is where I split the audience. For a professional, who meets the Bayonet regularly and has an analysis team behind him, 9...a5 is attractive only if it holds up at the very highest level. For a strong club player, who meets the Bayonet a few times a year and has no time to memorise hundreds of variations, 9...a5 has clear practical value: it moves the game into territory where understanding plans matters more than recalling lines. The contrarian angle lies in the product's central claim. Computers often do not know how to handle these complex strategic positions; that is the line used to sell the DVD. It is also a claim that is losing value over time. Based on my experience following games and comparing human assessments with engine assessments over many years, that gap has narrowed beyond easy recognition. Stockfish and Leela evaluate strategic positions of this type steadily. What was true when a DVD was produced may have stopped being true by the time it was sold. Age is the one variable that never lies, and for a static product, age is a sentence with no appeal. Correlation is not causation here. A position with few concrete variations does not automatically become safe for the Black player. It only means mistakes arrive more slowly, and the price is that you must read the plans correctly. Read them wrongly, and a strategic position punishes you later but harder, because you have no forcing move left to cling to. The opening is where the meta disappears before the data can be printed into a book. A static DVD cannot be updated after an engine finds an improvement. That is a structural disadvantage, not the author's fault. Garry Kasparov once kept the King's Indian Defence in his arsenal at the highest level, but that arsenal was updated continuously; a DVD is not. There is one more problem, and it belongs to the document itself. The headline speaks of a European schools chess event in Tsaghkadzor; the body speaks of an opening DVD. Two unrelated subjects. Under my three-source discipline, a document that contradicts itself at the structural level forces every conclusion drawn from it to carry a higher-than-normal degree of uncertainty. I cannot use that headline to say anything about a junior event, and I cannot use that body to assert anything about the strength of 9...a5. If you are considering adding 9...a5 to your opening arsenal, here are signals to track rather than beliefs to hold. The most valuable signal is the actual scoring rate of 9...a5 against the Bayonet in databases at 2600 Elo and above. If that number is positive, the move's credibility rises. If it is negative, it may still be useful at club level, but do not call it a weapon. Alongside it is the appearance of 9...a5 in recent elite games. A move only truly lives when someone plays it and wins. And the background signal, the one that sets the ceiling for everything else, is the frequency of the King's Indian Defence at the top level. If that frequency keeps falling, the commercial ceiling of any product built on the system falls with it. Numbers are asceticism: you must give up comfort before you can see the truth. The comfort here is believing that a strategic move is automatically safe, and believing that a headline is enough to describe a document. Both are loans with unpaid interest.