9...a5 Against the Bayonet: A Real Strategic Weapon or a Seller's Pitch?

Late at night, I muted the commentary on an online game, brought the board back up on the big screen, and rested my index finger on the a5 square. That is the move an opening DVD product is pitching as a "clear answer" to the Bayonet Attack in the King's Indian Defense. I have sat in front of thousands of games in this system over more than four decades, and I learned one very simple thing: when a seller calls his move "clear," it is usually because he needs you to believe it more than he needs you to verify it. The move 9...a5 is nothing new. It is a long-standing sideline, now dressed up as an invention. The real question is not whether it is strong or weak. The question is: who benefits from you believing it is "equal"? The questions I ask are not like a woman's, but the answers they dodge are not like a man's either. And in the chess world, people dodge exactly one question: where are the numbers? Let me rebuild the setting for those unfamiliar. The King's Indian Defense is the system in which Black yields the center and strikes back with ...e5 and ...c5. After the classic sequence 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5 7.0-0 Nc6, we enter the Mar del Plata variation, named after the 2026 tournament in Argentina. White has many ways to play, but the most ambitious is the Bayonet: 8.d5 Ne7 9.b4. White pushes the pawn to b4, launching an all-out attack on the queenside — the choice many strong players consider White's sharpest weapon. How does Black answer? The orthodox answer has long been 9...Nh5, a knight to the rim, threatening f4 and opening a series of forced lines where computer analysis becomes mandatory. The product being sold admits as much: after 9...Nh5, the position opens, the lines become forcing, and computer analysis matters again. That is exactly why they propose a different fork: 9...a5. A flank pawn strikes directly at b4, opens counterplay on the queenside, and shifts the focus to long-term strategy rather than a string of calculations. Sounds appealing. But slow down a beat. The first thing to state clearly: the product's central technical claim is a positional argument, not a theoretical refutation. The seller himself admits 9...a5 leads to sound positions with very few concrete lines, where the focus is on strategy not tactics, and — most importantly — that objectively the chances are equal. That is the language of a workable equalizing sideline, not of a refutation of the Bayonet. Buyers should read it as a practical, understanding-based repertoire, not a forced advantage. And this is where I have to stop, because I once misread a player's name, then read the position right when the slow-motion replay came up in front of my eyes. In chess, "computers don't understand" is a classic sales line, and it is systematically wrong. Modern engines handle Mar del Plata positions with ease. The product's own material contradicts itself: it says computers matter again in the main line, implicitly conceding that engines evaluate these structures well. You cannot advertise "computers don't understand" and rely on a computer to check the line. The genuine selling point — and it is a sincere strength — is the anti-memorization stance. Comparing 9...a5 with 9...Nh5, the seller is offering a low-theory, high-understanding choice. This is internally consistent. But it is a double-edged sword. Low forcing density means less risk of falling into a prepared trap, and also less margin for error if the buyer misjudges the strategic plans. A memorizer will go astray faster, not slower. One fact is easy to overlook: 9...a5 is not an invention. It is a line in the ECO E97–E99 family, long used as a direct strike at the b4-pawn and the queenside. It is not new. Only the packaging is. By opening classification, it remains a sideline, with a smaller theoretical footprint than 9...Nh5 — less to memorize, but also less refined. That empty stadium years ago, I found a tactical diagram lying quietly under a seat instead of the roar of the crowd. The lesson from the pandemic season, when I sat rewatching dozens of classic games for my podcast series, still holds here: a strategic position lives or dies by the player understanding the plans, not by that player remembering moves. If Black knows what he is doing, the position can quickly become dangerous for White — but that is an "if," and the "if" is not included in the box. This is where I have to say out loud what sellers do not want to hear. The biggest risk here is not technical, it is informational. Every favorable claim — sound, equal, dangerous for White if Black knows how to play — comes from the seller himself. No win-draw rate, no game sample, no engine match-rate, no ACPL. Not one independent number. During the transfer window, I still tell my audience that player agents are the biggest hidden cost, and the noise they generate distorts the market. In chess, the opening-repertoire author plays exactly the same role: an agent for a move, paid to make it look more attractive than it is. Where could I be wrong? If an independent database showed 9...a5 scoring equal or better for Black at club level, my argument would collapse and the product would deserve praise. But until that number appears, I keep my skepticism. Mistakes are not frightening; bending down to pick up the tape at 2 a.m. is what makes a forecaster. And I have not yet seen the tape. If you are a King's Indian player from club to master level, 9...a5 can be a useful tool — but verify it with your own data before adding it to your arsenal, and keep 9...Nh5 as a backup for critical games. And if you are looking for a refutation of the Bayonet, look elsewhere. The real value of this sideline is not that it is strong, but that your opponent is less prepared for it. A silent round of applause can kill emotion, but it cannot kill strategy. And in chess, the winner is the one who understands the position longer than the man selling the disc.