Guard pass troubleshooting summary/introduction to "theory of guard passing"

Let us compile common scenarios in which specific guard pass techniques fail. Surprisingly, almost all failures stem from not fully controlling the shoulders or hips in some capacity.

Back step: assuming that your right leg was the one caught in the half guard, and thus you draped yourself toward the opponent's right side with your left foot back stepping, your opponent can hook your right leg with the instep of their right foot and flip you over.

• Solutions:
• Dig your right elbow into the opponent's right crook of the elbow. Often, the aforementioned foot action requires assistance with their right hand, and doing this naturally distributes your body weight for pinning their right shoulder without you having to think about it much. Bonus points if you can somehow tilt their jaw up with your upper body in the process.
• Use your left hand to impede the leg action required for the reversals. 
• Remark:
• If you can get a really good crossface, that is good too, but if you cannot physically make the opponent's face turn away with your pressure, or worse, your opponent manages to resist the crossface by turning their face toward you, you have made yourself vulnerable to a machinery purpose-designed to handle this situation: the reverse half guard. DUN DUN DUN!

Double under: even if you have securely fastened the two underhooks, if you do not progress the pass fast enough, your opponent can fish out an arm and submit (triangle or omoplata) you. Also, slick opponents can even take your back off of this position.

• Solutions:
• On one hand, the double under pass is "safe" and it is a "slow, patient" pass that uses pressure. But, on the other hand, that kind of safety is only afforded once you successfully stack the opponent. Stack them ASAP, and do not hesitate to switch to a different position if you see something coming (remember- if you bail out on your own terms, you can still control the fight on your terms).
• Remark:
• If you have two underhooks but have not necessarily stacked your opponent yet, your opponent's hips and shoulders are still alive, which is why they have so many counters available.

Hip switch: assuming that your right leg was the one caught in the half guard, and thus you draped yourself toward the opponent's left side, if your opponent's arms are alive, they can flip you over.

• Solutions:
• Isolate the right arm by scooting your butt back just a little bit more, and isolate the left arm by digging into their left armpit or the crook of the elbow with your left elbow. Digging your elbow has the added benefit of significantly immobilizing your opponent's left shoulder because your body naturally shifts itself in such a way that weight is applied around the area. Bonus points if you can somehow tilt their jaw up with your upper body in the process.
• Remark:
• Getting the crossface can work, but it has to be hard enough for your opponent's face to actually turn away. Otherwise, it is nothing.

Knee cut: assuming that you slid over the right leg, your opponent somehow brings the left leg into play and start framing against you with it; you eventually find yourself reversed or even in a footlock battle as your opponent secures the "saddle" position. Even if you manage to clear past the left leg, if you do not control your opponent's shoulders, you can potentially get your back taken.

• Solutions: 
• If you really cannot get past the left leg frame, just retreat back into a staging position- like Headquarters.
• If you get past the left leg frame, lean your upper body a little so that they cannot leg frame against you again. Then, control the shoulders right away. By yanking on the opponent's right tricep, you can indirectly flatten out both shoulders while disabling the use of the right arm.

Leg drag: your opponent shifts their hips and gets the other foot on your hip. Or, your opponent somehow manages to squirm away from you even after you establish position.

• Solutions:
• The leg that you do not have a grip on should be splayed down- like when you are popping off that DLR hook and you point your foot outward to keep it down. This helps with hip control.
• If you simply leg drag against an opponent who has their feet up as in the open guard posture without setting up a good position, right when you start the drag with the two grips, your opponent's hips are very much alive at that point, which is why they can do that guard retention move. If you keep dragging the other leg, you can eventually out-speed your opponent, though. 
• Assuming that you dragged your opponent's right leg, after you trap your opponent's right leg in your right armpit, use your left hand to staple your opponent's right bicep. This achieves shoulder control.

Leg lace/leg weave: your opponent somehow managed to scoot away from you, or even worse, somehow omo plata'd you.

• Solutions:
• This is all because you either did not get the collar grip, or your opponent broke it successfully. Establish the collar grip first before you attempt to secure side control, and even then, do not lose the collar grip. Use your head to flatten out the shoulders ASAP and shift the weight balance such that your hand is "heavy" for the opponent.
• Remark:
• The collar grip is critical for bolstering shoulder control. You may have flattened the legs and controlled the hips, but your opponent's outside shoulder is alive without your head flattening it, which is impossible without anchoring yourself with the collar grip.
• To help flatten out the opponent, pull on the collar as you push in with your head.
• Once they strip the collar grip, you literally have about 1 second to get it back and flatten them out. Otherwise, just retreat before you get caught in something slick.
• In no-gi, utilize the bicep grip for similar results as the collar grip.

Long step: your opponent turns into you with their frames up immediately after you do the characteristic long step movement. Worse yet, your opponent somehow breaks your grips and shrimps away.

• Solutions:
• Due to how your body must move when you do the pass, there is a brief "gap" in which you do not quite have shoulder control. After you long step, tripod up on your feet and drive in with your head to flatten out the opposite shoulder ASAP. Better yet, position your upper body a tad closer to your opponent before doing the long step, and do not be so uncontrolled and brash that you hurl yourself so far out of range with the movement (on the other hand, you do need to give it some gas to defeat the last ditch crossed feet in the first place). 

Over under: assuming that you got the underhook on the "under" leg, and straddled or trapped the "over" leg, your opponent somehow managed to frame against your hip, shrimp away from you, or worse, roll you over. Even worse, they took your back, got a kimura, or even both as in the "kimura trap".

• Solutions:
• Do anything and everything you can in order to get your head parked in the right spot as soon as possible. If your head is not parked in the sweet spot (i.e. right in front of the underhooked leg, resting right on top of the pelvis), your opponent has options. This is one of the two fundamental weakness of the pass itself. Rest assured that once your head sits there, even Marcelo Garcia struggles to recover guard (watch the roll vs. Faria).
• Hold snugly with your overhook arm- no spaghetti elbow!
• Use weight distribution to keep the opponent's shoulders pinned as you secure crossface.
• Assuming that your left arm is the overhook arm, slide your left forearm and elbow across their torso until you are close enough, and then snake your left hand underneath, keeping the underhook strong to prevent shrimping. This keeps your opponent pinned down as you secure side control despite not having real shoulder control, and helps hide your overhook arm from counters. Keep the left arm bent, your shoulders almost brushing along the opponent's torso as well.
• Never reach across in the air toward their head. Your opponent's shoulders are still free, so they can easily get up and counter you yet.

• Remark:
• Once you glue your head on the sweet spot, you need to apply enough force to keep your head glued there. Likewise, your opponent really wants to slide your head off of their hip, and their low-hanging-fruit reversal options require having brushed your head away. Remember: if your head is not in the right place, you are screwed.
• When you slide your overhook side shoulder across, watch your weight distribution; otherwise, your opponent can very easily flip you over, gi or no gi.

Side smash: your opponent somehow manages to get their upper body off the mat, frame against you, and scoot away.

• Solutions:
• After you get the leg action going, drape yourself over their body right away to staple the shoulders as soon as possible. Be ready to swat away your opponent's arms in the process. You may have gotten past your opponent's legs and compromised your opponent's hips, but their shoulders will have stayed alive until you address them, which is why they can get up in the first place.

Rather than memorizing all of the special cases like this, you can in fact, generally anticipate and address your opponent's defensive and counter-offensive options by knowing what layer of defence you are working with at the moment. Stay tuned.