I've been taught and seen it almost universally accepted as the weak point of blocking when your elbows are point out. So when your thumbs are pointed inward.
- What I've been taught and mostly seen over the years is thumbs up = elbows down. Harder for the DL to disengage and break the arms.
- I've also seen the double-under approach or now what's classified as the Tip of the Spear model. Thumbs out in a W, still, elbows are not out, and creating lift, displacing the momentum of the defender.
I've heard very few talk about hand placement as thumbs in. I've seen a few equate it as how would you stop a door?
My personal preference and opinion is to keep elbows from point out as it's easier to collapse your arms and defeat the block. That's just me.