King's Indian: The 9...a5 Move Against the Bayonet Attack and the Data Gap in an Opening Recommendation

The day I reopened this analysis file, the first thing that stopped me was not a chess move. It was a data error. The document's headline read: "From Tsaghkadzor to the Grand Final: European Schools Chess Champions crowned amidst cultural celebration." Its entire body — eight information points, nothing more — discussed an opening DVD recommending the move 9...a5 against the Bayonet Attack in the King's Indian Defense. Two unrelated subjects in a single file, with not one sentence connecting them. In my trade, a file like that has a name: an editorial error waiting to be found. But it also carries a different kind of value, if one is willing to set the headline aside. What remains, however thin and unsourced, still contains a technical question serious enough that a data journalist like me has to sit down with it: is 9...a5 genuinely a usable option against the Bayonet Attack, or just a sales pitch dressed in strategic language? People call it a shock; I call it data that has not been read. And the data here, unfortunately, is missing precisely the thing that matters most. To understand why the question matters, it has to sit in the proper stream of the King's Indian Defense. The KID is a hypermodern defence: after 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5, Black voluntarily concedes central space and counterattacks with pressure on the kingside. The classical Mar del Plata line with 7...Nc6 is one of the sharpest branches of this system, where the two sides race to attack on opposite wings: White advances on the queenside, Black masses force on the kingside. It is no accident that this is one of the last refuges of players who prefer to fight with structure rather than with memory. Against that backdrop, the Bayonet Attack — White's 9.b4 — arrives as a space-gaining jolt. White pushes the b-pawn to claim queenside ground, disrupts Black's plans, and forces an immediate answer. It is a fashionable move in the literal sense: it has appeared steadily in top-level events for decades, and every KID player must carry a reply in the pocket. Black's orthodox answer is 9...Nh5. It opens the kingside, brings the knight to the rim, and steers the position into concrete, calculation-heavy lines where engines feel especially comfortable. In other words, 9...Nh5 pushes the game toward whoever remembers more lines. For a club player with no time to grind through hundreds of variations, that is an invitation into a labyrinth. And it is precisely into that gap that the DVD inserts itself. Which is why I did not dismiss it out of hand as empty advertising. The document's positioning is clear: instead of 9...Nh5, Black should play 9...a5. This is not a new move. It is a sideline that has appeared sporadically in top-level play as a space-gaining, tempo-gaining option — pushing the a-pawn to hit the b4-pawn while preparing ...c5 or ...Be6. What is new is the packaging: presented as a complete solution to the Bayonet problem, not as a fallback for low-stakes games. The product's central argument consists of four propositions. First, 9...a5 does not force the position into rigid calculation. Second, it leads to purely strategic positions where understanding plans matters more than memorising lines. Third, the number of concrete variations in this branch is small, sharply reducing memorisation load. Fourth — and this is the most notable proposition — computers often do not know how to handle such complex strategic positions. Purely on technical grounds, the first three propositions are not unreasonable. A branch less eroded by theory genuinely can save preparation time, and for an amateur that saving is a real, measurable benefit rather than a slogan. But this is where I have to put down the pen and open the database. Based on my experience following top-level King's Indian games over many years, I always ask three questions before any opening recommendation. First: what is the engine match rate? In other words, if Stockfish analyses this branch, what share of moves coincide with the machine's top choice? The document gives no figure. Second: what is the ACPL — average centipawn loss — for both sides in this branch? Also none. Third, and most important for a practical recommendation: what are the actual win and draw rates for 9...a5 above 2600 Elo, over how many games, in what period? The entire answer is silence. Numbers are asceticism: you must renounce convenience to see the truth. An opening recommendation without engine data, without sample size, without practical scoring is, technically, a hypothesis. A hypothesis can be correct — I do not rule that out. But it has not been verified, and it is being sold as a conclusion. More telling still is the document's final assessment: 9...a5 is described as objectively equal, but practically dangerous for White if Black knows the plans. That is a clever formulation. It concedes that the practical numbers do not favour Black — equal means nobody is ahead — while shifting all the value into a category no data can refute: human understanding. And here is the crux. If both branches are objectively equal, then the value of 9...a5 lies not in the position but in the fact that your opponent encounters it less often. That is a psychological edge, not a theoretical one. Such edges are real — I have written about them often enough not to dismiss them. But they have a short lifespan. The moment the move becomes popular, the moment an analysis video passes a few hundred thousand views, the moment a new engine is updated, the edge vanishes — while the position stays equal. In other words, this is not a theoretical invention. It is an old sideline being repositioned. And repositioning, in chess, is a marketing skill, not an opening skill. The fairest thing I can say about this product is that it targets a real segment. There is a group of players — I call them the strategists — who find themselves crushed between two millstones: opening theory ground down to the last percentage point by engines, and the limited preparation budget of a working adult. For them, a branch with few lines is a gift, even if it is not theoretically superior. I understand that feeling. I have sat for hours over a simple position wondering whether I understood it or merely remembered it. The answer, most of the time, was remembered. This is where I have to say plainly what most opening-marketing documents avoid: the claim that computers do not know how to handle complex strategic positions is the weakest of the four propositions, and it is weakening over time. Fifteen years ago, one could still say it. Older engines sometimes undervalued closed KID positions, where value lies in pawn structure rather than immediate tactics. But that era is over. Stockfish and Leela evaluate strategic KID positions reliably, and they do not need to understand plans the way humans do — they only need to evaluate correctly. That a club player finds the engine's assessment hard to grasp does not mean the engine is wrong; it usually means the player has not read the assessment yet. This is where correlation and causation part ways. The 9...a5 branch is rarely played. But rarely played does not mean undervalued. Many sidelines remain rarely played simply because they are not better than the main line, not because they are misunderstood. The document does not prove the difference between those two possibilities — and that gap is precisely what its entire argument stands on. In the larger picture, the KID is seeing declining frequency at the top level in the engine era, as many leading players shift to defences less theorised. That does not make a KID product meaningless — it merely narrows its commercial ceiling. A sideline within a shrinking system is a branch of a branch. That is a market fact, not a technical criticism. There is another layer I cannot skip, because it falls squarely within my expertise. This product exists as a DVD — a static format, printed once and done. Meanwhile, all opening knowledge is migrating to subscription platforms that can be updated continuously. Esports is where the meta disappears before the data can be printed into a book — and chess, at a slower tempo, is walking the same road, only a few years behind. A DVD cannot correct a move after a new engine finds a hole. That is a structural disadvantage, not a minor detail. And that disadvantage is not merely technological. It bears directly on the product's technical value. An opening branch survives because it is tested, corrected and updated continuously. An opening branch frozen on a disc can only be correct until the day it is published. Age is the one variable that never lies — true of a player, and equally true of a media format. I set myself a seven-season horizon. That is, when judging an opening branch, I do not ask how many games it wins this month. I ask how long it can stand after the theory around it is rewritten. A sideline like 9...a5 might live seven seasons if it genuinely contains durable plans that humans grasp better than machines. It might also die within two if its only value is unfamiliarity. To verify that, I need three genuinely independent sources: a top-level game database, an engine assessment at sufficient depth, and a plan analysis by a named expert. This document gives me one source, and that source is anonymous. I cannot publish on that basis. Back to the original file. The data error in the headline is not just an editorial mishap. It is a reminder of how we consume chess information. When the headline speaks of a schools championship in Tsaghkadzor and the body speaks of an opening DVD, one of the two has almost certainly been mislabelled. Careful readers will notice. Hasty readers will misquote. In my trade, that is the line between a journalist and a copyist. Three sources does not mean counting three names. It means checking whether all three rest on the same underlying figure. With this document I have one source, and that source contradicts itself. By my discipline, that is an unpublishable state. So what is the signal for the next cycle? If 9...a5 is genuinely usable, we will see it in top-level events, and more importantly we will see it scoring positively above 2600 Elo in a sample large enough to mean something. If that does not happen within two seasons, what we have is not a new opening branch but an old one repackaged. And if it does happen — I will be the first to correct my notes. That is the only way a data journalist stays loyal to the number.