imo, pac is more dangerous now than before, not in the sense that he's gonna knock you out with 1 punch, but now he's more technical with his approach but can still unleash hell when the opportunity comes. he's not that wild 100+ punches per round fighter anymore.
The term "split entry" comes from Dan Inosanto's mixture of martial arts. It's not a boxing expression.
In boxing this is just called a slip counter. Or a slip and counter.
Good move nonetheless.