Ill have to think more on it. Barrera does a type of block naturally (without thinking), you'll pick it up in one or more of the trilogys against Moralles.

When they are banging it out you will see that after taking a few and uncertain where Morrales is going to come from next, AMB puts a lead arm straight out withhis head in behind the shoulder and turns into Morrales like a search but youll notice it takes control because he has shifted his center line into the line of action with a feeler out.

Koysta used to use a feeler arm alot too, but not so much his center line he used to hide his intention behind his.