I came to think of the fact that in a sport like tennis its a great advantage, when playing against left-handers (southpaws), to have been brought up against them. I think Kessler in his early carreer sparred quite a lot against the southpaw Mads Larsen(?), a world class fighter at the time. So I guess I'm throwing the question out for people to answer whether this translates into a substantial advantage for Kessler?
if you're asking whether simply sparring with a southpaw will improve your chances then probably not. jeff lacy sparred an awful lot with winky wright prior to his fight with calzaghe, didn't seem to help him much.
More having trained against them early on. I remember from playing tennis some years ago that the guys who had trained against left-handers in their teenage and younger years almost had a knack for playing the balls in difficult places for the left-handers. To me it seemed as if they almost had it hard-wired into their game. So I was wondering if something similar could translate into boxing in some ways and potentially give Kessler an advantage. Could it be that Kessler is a natural "southpaw killer"? Also: Are there any previous examples in boxing of southpaw killers?