I love Willie Pep. Bruce Lee took a liking to him, as well as Ali and was influenced by the way boxers moved. If I'm not mistaken Lee was originally a linear fighter, and his introduction to lateral angles came from a friend of his who was an amateur boxer that he sparred with. Lee was an advocate for boxing.
Another thing Pep did well was head movement. If his feet weren't moving his head was moving. If not those then his hands. Fighting is largely about rhythm. He was comfortable in his movements which came from tons of practice. There are different types of footwork. Pep's established his ability to move quickly, and freely.
Planting your feet to pivot and bang is also footwork. Many fighters forget the pivot to generate power. Footwork is one of my favorite aspects of the fight game. You can tell if a guy knows his stuff if he's watching your feet as you train (most coaches do this). I look at a guy's footwork first when sizing him up.