For some reason, certain fighters become better when donned with a championship belt. Before that moment, they were not known as great fighters and some were heavy underdogs in their title winning efforts. Some of us think, "Give him a rematch with the champ and we'll say goodbye just as fast as we said hello." But he surprises us. Here are some fighters who I think fit this catergory.
(1) Lupe Pintor: Watch his fight against Carolos Zarate for the "Bantamweight Championship." Great fight. Lupe lost. No ifs ands or buts. He lost and was given a decision he didn't deserve. However, check out the rest of his career. The war with Wilfredo Gomez, the awesome defenses of his title, etc. This was a man who loved the way a Championship belt looked around his waist and was willing to kill or die to keep it there. HOF fighter.
(2) Muhammad Ali: Hate to keep on bringing Ali up but let's face it, everything that could be said, has been said about Ali. Why was he a 7-1 underdog against Sonny Liston? Well for starters, he was knocked down by Sonny Banks and Henry Cooper. He had a fight against Doug Jones that could've gone either way (A good amount of the boxing press thought Jones won). Looked like somebody played a joke on some 22 year old loudmouth and told him he could do things he just had no chance to accomplish. Clay (Later Ali) outclasses Liston in one of the greatest boxing exhibitions I've ever seen. He goes on to outclass Patterson, Terrell, Folley, Williams, Chuvalo, Cooper, London, and Mildenberger to name a few. If you're not impressed with that group, try the 70 Ali victims, Foreman, Frazier, Quarry, etc. Yeah, the belt made a difference in this man's life.
(3) Larry Holmes: On the way to the his challenge of Ken Norton for the WBC HW Championship, Larry was inconsistent. One good performance, a couple of pointless efforts, suffered a few knockdowns, etc. Seemed to come into his own in the first Shavers fight when he was promised a bout with Norton upon winning. He beat Shavers for 12 rounds and looked like a different fighter. Once he won the WBC title, it can be said that he defended it with his life. Who he fought and failed to fight may be debated upon for years, but one thing is for sure. During the 20 times Holmes defended the title, it was obvious that he had to damn nearly be killed in order to give it up.
Give me some more fighters that fit the bill. I left out Eusebio Pedroza in the hopes that somebody else would mention him.