Working Cross-Sides Top, noticed if the bottom player places their far-side forearm under the neck prematurely, they open themselves up to elbow control demonstrated by Braulio Estima @ 10:30 and 9:41-10:09:
To prevent the above elbow underhook, experimenting with folding the forearm across belly, which shuts down the bicep access at the fold of the elbow that makes control work.
Footnote: First heard about arm-fold posture second hand from some one who saw Rigan Machado teaching it in LA in the early 2000s.
Further, although I couldn’t find any youtube footage, Saulo Ribeiro teaches arm-fold posture extensively in his Jiu-Jitsu Revolution 1 DVDs, and in his Jiu-Jitsu University book from which I found a page and small photo of it in action:
What you can’t see is Ribeiro’s forearm tucked in at a 90 degree angle in between chest navel area. Something I didn’t understand about this position is that arm becomes active when you bridge, with elbow pushing at opponents south shoulder/upper chest (middle pictures) to facilitate shrimping.
Is this posture the end all be all? Certainly not. For right now, I think the standard forearm frame against the neck is great at longer ranges, or to help create space when you’ve lost a grip battle and your training partner is intent on holding you down and crushing you. The Arm-Fold comes in to play during moments when we’re dominated with body-weight but grips haven’t been established.
One a side note, I think we often look for the perfect posture instead of understanding window(s) where specific postures are most useful. From here, we can us a variety of frames like Kung-Fu to stifle, shut down, create space, recover, and reverse the top player should the opportunity present itself. They’re a doorway to being sensitive, fluid, and dynamic: