Not retracting the jab?

[Andre]

There is one instance it works ok on. You used to see Kostya do it on the move and occasionally Barrera would (maybe subconsciously)pull it out of the hat when fighting nose to nose with Eric,but his was more using the already expended arm as an instant block by turning it in to disrupt their shot without having to break from the nose to nose distance(same can happen by dropping your elbow down into the cook of their elbow) that allows you maintain close distance.

Kostya would consciously use it for a feeler though. In Kostyas case;You walk in with it right in their face and hide out on the angle from it while leaving it in their way; then go for them off their reaction. Or you throw the jab and if they dont react,you leave it out and shift your body on the angle so your extended arm is in the way of their lead arm and lays across its trajectory path, but you gotta know that is exactly when you throw your rear arm down the pipe or move in closer and hook in front of their rear and beat them to the draw, cause its rear arm verses rear arm right then but you have the leap on them and the turn or foot shift or both already set up for the power shot.

( I find it strange that the writer mentioned Kostya; but only Kostyas right hand as an answer to it, not his actual technique of using it to his own advantage.