The key is to hunch up your shoulders so as to attach your head to your body. Makes your head sturdy and covers you up more. for orthodox take your right arm and bring it up across the face so that the forearm is coming across your nose and your right shoulder and tricep is blocking your right ear/cheek. With the same arm make it so that your glove is faced up to cover as much of the left side of the face as possible. The palm will face outward. With the left arm put it across your body so that the forearm comes across the belly over the solar plexus. Your left kidney and liver will be exposed as your arm will not be able to wrap all around the body that far so you will have to either alternate from blocking right hands to your left kidney with your elbow or left hooks to the body with your glove. The final touch is to slighty bend the body forward so that you are not straight up in the air. It makes you less of a target. Remember that though you are covered up well you will still want to roll with punches.


Notice that your arms are committed to blocking and aren't in a position to punch. Also note that from this stance your right temple is exposed and can be blocked by raising up your tricep/elbow over the temple but that this motion will expose the bottom part of your face. Your body's ability to move is also hindered as the stance makes you very stationary. Though you seem very protected there are areas on you that are still exposed (your arms can't block everything) and that to defend that exposed area is to leave open another area. Thats the big problem when you have an alternating guard. It makes you leaky.

I'm not a big fan of this stance. I'll do it sometimes upon miss a right hand but other than that I personally don't like it. That crab style is pure defense and to my mind a pretty leaky one at that.