9...a5 in the King's Indian Defence: An Antidote to the Bayonet Attack, or a Marketing Promise?

A promotional blurb for a chess course DVD contains a sentence — and in it there is no engine evaluation, no cited game, no player's name. Just one claim: after the Bayonet Attack (9.b4), if Black plays 9...a5 instead of the main line 9...Nh5, the resulting complex strategic position is one "computers generally do not know how to handle." Inside that single sentence hides a two-decade-old idea — one that draws a line between understanding and memorisation, and hands the buyer a small piece of comfort. For me, the sentence's weight lies not in its data but in its absence: what is missing — engine evaluations, sample games, the presenter's identity — tells us we are selling belief in the place of information. The King's Indian Defence (KID) is a hypermodern opening: 1.d4 Nf6 2.c4 g6, ...Bg7 — Black deliberately concedes the centre, then attacks it later. Its sharpest branch is the Mar del Plata Variation (7...Nc6, then ...Ne7, ...f5), where both sides build attacks on opposite wings. White's Bayonet Attack — 9.b4 — grabs queenside space and disrupts Black's familiar kingside rhythm. For years it has been a White standby, and at elite level "fashionable" — which here means it creates demand in the preparation market too. Black's main answer is 9...Nh5: open, forcing, computer-determined. This is where the politics of the engine era begins. Where forcing moves are many, the memorisation load is heavy, and the human sitting at the board carries a higher risk of error. The market then looks for an alternative. 9...a5 is that alternative — less forcing, more strategic, supposedly a game of "understanding." I follow the transfer market the way a meteorologist follows pressure fronts — and the chess opening market is just the same: a low-pressure tug between a fashion and its antidote, where every new course is really capitalising on a preparation asymmetry. The first thing that strikes me: there is almost nothing to analyse. No player, no event, no rating, no engine evaluation, no ACPL, no database win-draw rates, not a single sample game. The technical claims are essentially the author's opinions, not objective facts. That vacuum is itself data: the instructional chess market still sells products that lean on a tone of authority instead of proof. I sat in the anchor chair and learned that silence is a production cue — and the silence around engine data in this blurb is exactly such a cue, telling us what the marketing wants to hide. Read carefully, one defensible claim survives: after the Bayonet (9.b4), Black's main line 9...Nh5 is open, forcing, engine-driven; 9...a5 is a less forcing, strategy-centred alternative. That claim is not in itself contentious — the normal rhythm of opening theory is a duel between a fashionable White system and Black's antidote to it. At the 2026 Moscow set-piece desk I learned that the true value of preparation is set by how prepared the opponent is — on the scouting report, not on the board. The same holds here. But the biggest claim is outdated. "Computers do not understand these complex strategic positions" — that sentence is now nearly dead. Modern neural-network engines (Stockfish NNUE, Leela Chess Zero) handle strategic manoeuvring in the KID with exceptional skill. So the sentence is not a technical statement but a marketing device — a tool to flatter the human buyer. There is, in fact, an internal contradiction: on one hand the claim that computers do not understand these positions; on the other, the concession that after the main line 9...Nh5 "computer analysis becomes important again." Elsewhere it is asserted that in 9...a5 "objectively the chances are equal," yet simultaneously that it is "dangerous" for White. Those two sentences cannot both hold, unless we read them as practical framing: objectively balanced, but uncomfortable for the unprepared White player. The reasonable reading, then, is this: engines are not weak — the 9...a5 lines are simply less forcing, and therefore less engine-decisive. This is a claim about human practical difficulty, not engine incapacity. And here lies the real commercial strategy: 9...a5 is aimed at unsettling the White player who has prepared the main 9...Nh5 lines in depth — it exploits a gap in the opponent's preparation rather than claiming an objective advantage. From decades of watching games at the board, I can say this kind of "surprise weapon" changes a game psychologically, not the results column. In blitz or fast time controls its effect is sharper, because the opponent has no time to analyse — but that is not part of the product's claim, and that is exactly where the accountability gap sits. This opening-theory fight is, in truth, a pressure flow much like the transfer market. Elite practice creates a fashion; the fashion becomes a question for opponents; then the repertoire-product market starts hunting for an answer; and finally the club player buys that answer too. The Bayonet is the fashion; 9...a5 is a proposed answer to it. The only question is whether that answer is an antidote, or merely the advertisement of one. "Objectively equal" — in engine language that means an evaluation near zero, and the burden of proving it falls on the seller, not the buyer. In reality, many KID sidelines evaluate slightly worse, yet remain practically playable. But the source contains not one evaluation, so this claim sits closer to speculation than to fact. There is a further layer: format. The word "DVD" is itself a signal. The instructional chess market is now migrating toward interactive platforms, where every line is engine-checked and every claim is matched against a database. The classic DVD format then survives for an audience that prefers explanation to evidence. The choice of format alone suggests the product's technical premise is probably pre-NNUE, or aimed at an engine-agnostic audience. From here I want to walk in the opposite direction. The question is not "is 9...a5 equal?" — the question is to whom, and why, this kind of product is being sold. The DVD's core sales message, "think for yourself, don't memorise," is an evergreen marketing archetype that touches adult improvers. In South Asia its pull is stronger still. Standing between India's ecosystem of 80-plus grandmasters and Bangladesh's five GMs ever, one sees how comfortable and how fragile the call to "understand" really is. In a country where the school-chess pipeline collapsed in 2026 and government support is capped at roughly Tk 11 lakh a year, this course is affordable to a club player — but a "play by understanding, not by engine" message resting on unproven authority becomes a stress test for chess-teaching method. Are we actually teaching people to think, or selling them a comfortable excuse? Before buying, the sensible steps are simple: run the critical 9...a5 lines through a modern engine, check White's score in a database, and keep this as a surprise weapon in one's repertoire rather than a main pillar. The mistake is treating this line as equivalent to 9...Nh5. In practice it is an instrument of preparation asymmetry; and like any instrument, it goes stale when the battlefield changes. The most real risk is technical overstatement, but its impact is limited — this is a static product, not an event in a competitive or financial ecosystem. Still, there is an opportunity-cost risk: a buyer who, without proper understanding, replaces 9...Nh5 with 9...a5 as a mainstay may get practical results worse than the blurb promises. A devoted community for the King's Indian Defence still exists, and it will buy this kind of specialised content — a small positive for opening diversity. But the gap between that devotion and the product's claims should not exist. Back to the sentence I began with. When an NNUE engine can verify every line in seconds, a teacher's real duty is not to offer comfort by saying "the computer doesn't know" — it is to show which lines are less forcing, where human practical discomfort arises, and how to convert that discomfort into honest preparation. I leave the question open: when will the next generation of opening courses print engine evaluations and database scores on the very first page — or will we keep buying the "understanding versus memorisation" story for another decade?