One thing I've touched on several times but never really gone into detail about is bringing a Rock list to a tournament. Now, when I say a "rock list," what I mean is any list that focuses on throwing a couple overwhelming threats in the enemy's face and relying on them to effectively pull the weight of the whole army. Double-Land Raider or Stormraven lists are the most commonly-seen version of this, but Nob Bikerz, Tyrantstar, Abby and Friends, Fatecrusher, and many others are all modeled on this same template. They have a small number of powerful threats and they hope to basically just beat your face in with them.
Why is that a bad thing? Well, it isn't always, but it has some troublesome implications, as we'll see.
If you're trying to win a tournament, the first thing you have to keep in mind is luck. Luck is always a part of this game, and there's really no escaping it. Every 40K player has a story about some game or other that they won (or lost) on some bizarre string of sixes-followed-by-sixes that, from the standpoint of "average" dice rolls, should never have happened.
But that's the thing- "average" dice rolls are something of a myth. They represent the single highest probability, but the truth is that the sum of other probabilities (that is, every non-average dice roll) is always greater. In layman's terms, the dice do crazy-ass things sometimes, and that's just the way of the world. It happens, and you just have to roll with it and keep playing. For most armies, this is why we build redundancy into them, so that a single poor dice roll does not get rid of our ability to kill tanks, or take objectives, or whatever it may be. We build redundancy into them to the highest degree because we want to be as resistant as possible to bad luck.
Rock lists, on the other hand, can't do this. You can't have four or six Land Raiders in an army just in case the first one blows up; points won't permit it. By their very nature, they are investing all their resources into a small number of "chances," and if you lose one of those chances (to a lucky glancing hit, to a failed morale test, etc) you may just be out of the game.
This lack of effective redundancy and vulnerability to the whims of the dice gods is a major strike against rock lists as a competitive choice. Not because they can't win- indeed, they can, and those same factors that make them liable to lose can also occasionally grant them victories they shouldn't have managed, but rather because chances are, over the course of a five or six or seven game tournament, the dice will turn against you at least once and kick you out of the running for first place.
Compounding on this is their nature, and indeed where the name "rock" comes from, the classic game of rock/paper/scissors. Rock lists have weaknesses and strengths, both exaggerated beyond those of normal lists; they focus all their energy into a single strategy and damn the torpedoes. Against anyone not prepared to deal with is, this can be overwhelmingly good, but the flip side of that is that there is always a paper. If your Land Raider list comes up against Dark Eldar, you are basically boned and have very little chance of victory. Of course, every list has its weaknesses, but in investing so much into such a specific strategy, the rock list becomes insanely vulnerable to its counter, as it lacks the backup options and alternate plans that a more balanced force might be able to use to pull off a victory.
So, when you are looking at a win/loss/draw tournament, a rock list is often going to be a subpar choice because hoping to get through the entirety of your matchups without A, ever getting poor dice on your side or hot dice on the enemy's side and B, hoping never to face your metaphorical "paper" matchup is going to be very tough. You can do it, and certainly people have in the past and will continue to do so in the future (especially at smaller or less-competitive tournaments where these factors are less relevant), but you're betting against the odds.
W/L/D are not the only kind of tournament around, however. In fact, they're not the most common type at all- battle points are far, far more common in the 40K scene. And, interestingly, rock lists can do rather well at BP tournaments.
For one, losing a match in a BP tournament doesn't necessarily knock you out of the running. It is, in fact, entirely possible for you to lose to a player in a particular matchup and then come out ahead of that player in the overall tournament- even if you lose to them in one of the final rounds of the tournament.
For another, rock lists are particularly good at scoring overwhelming victories, which BP tournaments tend to reward strongly, especially wipeout victories (which often earn you the maximum number of points for the primary objective.) The nature of the rock list means that its wins tend to be somewhat all-or-nothing, either crushing the enemy quite badly or losing because they had an effective counter to your strategy. If you can rack up huge numbers of points off of those rounds you do win, any rounds you don't win may be less critical to your overall score (though still relevant, obviously), as it's unlikely that anyone will score the absolute maximum number of points, or even anything close to it, every round.
In summary, I'm not saying that you shouldn't run a rock list at a tournament, but like any other aspect of the game, you should go into the decision knowing what it means for your list and your game. You may find the above factors dissuasive or intriguing, but in either case it's important to understand what they are and how they relate to the game.
