why the boxing guard was adopted by PKA

PKA did something very revolutonary back in the day- it combined karate with boxing. what was it about boxing that made it so undeniably an effective addition to the PKA arsenal?
first, the boxing stance is more mobile. the forward, back, as well as the pivot steps were the quickest ways to move in and out, and in the case of the pivot, a good way to turn offline from roundhouse kicks to the ribs.
but the hand position itself is time tested- one hand covering each side of the chin, elbows in to cover the ribs- the stance itself is in effect a block.and one only has to make a tiny adjustment to cover any open spots. plus the boxing guard is "hit one cover three", meaning that as you jab, your jab shoulder covers one side of your chin,your other hand covers the other side, and that elbow is covering your ribs. contrast that to more traditional ways of punching which almost always leave a lot of openings, and one can see that the boxing stance was an easy choice.
the effectiveness of PKA techniques is based on their being ring tested. fighters like benny the jet, bill wallace, and don wilson took what worked. they worked out the BEST ways to deal with each kind of attack. these methods may not be the prettiest, but they are definitely the coolest.