I was thinking that one of Pacs biggest edges is that he's a southpaw. Most people would agree they're difficult to fight. It's hard to get your head used to puches coming from different areas. It's just awkward. Who actually seemed to do as well or better against southpaws? Off the top of my head Kostya Tszyu comes to mind.
Wlad Klitschko. He easily beat Ibragimov, Chagaev, Byrd, and Thompson....all four were top ten ring magazine ranked guys, and in three cases alpha bet world title holders.
Tszyu, Hopkins and Lopez all come to mind. Three technically superb fighters who didn't seem to be bothered by southpaws at all.
Hopkins was the first to come to mind - other than losing to Calzaghe - he beat every other Southpaw he's faces. And the Calzaghe fight was pretty close.
Wlad had an significant reach advantage over Chagaev, Bird and Ibragimov (who wasnt fighting anyway) which negates the advantage being an southpaw. I dont want to belittle his accomplishments but defeating southpaws which have the same reach than oneself is a completely different story. And if I remind you of the Sanders fight. Sanders caught the Klitschkos both with the standard counter punch of all southpaws the left cross over their straight right. After that it was a matter of chin.
No one dominated southpaws more resoundingly than Kostya Tzsyu. His straight right hand and his ability to put southpaws on their heels is what made him super effective.