Why did he vacate the IBF title and keep the WBO? I don't know how many more fights he had at 168, but I know he fought a few more times at that weight.
Obviously so's not to pay any needless sanctioning fees. The WBO was his belt, that he'd defended, what 20 times? Calzaghe was no fool. He didn't need no hype job's belt for people to know he was the man at 168.
Well it was either that or he didn't want to fight a mandatory..and doing a little research, looks like it was the latter: http://www.mma-zone.com/2006/joe-calzaghe-relinquishes-ibf-super-middleweight-title/ November 27th, 2006 By Jason Kim: Rather than fight the mandatory IBF Super Middleweight challenger, Robert Stieglitz (29-0, 19 KOs), Joe Calzaghe has decided to give up the IBF belt, choosing instead, to fight Peter Manfredo Jr., (26-3, 12 KOs) a fighter mainly known for being on The Contendor, an American reality based television program, which pits different boxers against each other. According to Calzaghe, he didnt see the point in fighting the undefeated Stieglitz, considering that he was only popular in Germany. So he dropped it to duck Steiglitz :deal Lol, if Steiglitz ever amounts to much I can see Calzaghe's detractor's bringing this up as an obvious duck
I recall some fuss about him fighting Peter Manfredo just to become better known with the american audience. Stieglitz would have been a better opponent than Manfredo, but still no match for Joe.
Zaghe just beated Lacy and later went on to beat Kessler and Hopkins, cant see why he should fear Stieglitz...
He won the "Ring" belt after beating Lacy, which essentially meant that he was recognized by the hardcore fans as the champ. US viewers don't give a rats you-know-what about ABC titles or Robert Stieglitz (who later got KTFO by Andrade and Berrio). Calzaghe (or Warren...) knew that.
He took the Manfredo fight over the mandatory defense because it was meant to set up a fight with Jermain Taylor.
No one cared about the Steiglitz fight and he was a weak mandatory. Calzaghe wanted the exposure and payday of the bout with manfredo.