The Catch is a combination of a light check with an avoidance movement. The hand is more used for keeping track of the incoming attack and its range than catching solidly its blow.
	The Bob and Weave is used to avoid a circular strike to the head. Your body bobs downward just enough to clear the line and allow your head and shoulders to weave under. Rick Faye says the head should “ make a smiley face motion” while dipping under the attack.