During his entire 10-year professional career, besides stage victories, Pantani won only 2 out of over 30 most important races available each year. 4 out of his 16 stage wins in the grand tours were tainted by the proven use of doping in the Giro from which he was expelled and one, on Mt Ventoux, was a gift from Lance Armstrong.
His bronze medal in the World's was marred by the positive doping test result in a race a few days later (65 hematocrit reading). These are the palmares of one of the greatest cyclists in the history of mankind (I almost forgot one stage win in the Tour of Suisse). Let's not forget that he begged his colleagues not to boycott the Tour in which he was the leader.
Why did he dope in the Giro after such easy victories in the previous one and the Tour? Why did he fail to win these races previously or afterwards? The answer is, that, without doping, he was a man of very limited capabilities, his sole cycling talent being a relatively brief spurt (a few kilometers) up the final climb.
Consider this: He never won the red polka-dot jersey in the Tour (one must be consistent to do it). Outisde the 2 tours that he won and the one that he was caught in (all three back to back), whenever he tried to attack at an early phase of a mountainous stage, he was caught, usually losing much time to the leaders or flatly abandoning the race. Even if he attacked too early on the final climb, he was likely to be caught and passed by others (eg. by Indurain, Leblanc, Ullrich). That's also why he never won a mountain ITT. Such stages were too long for his stamina. Similarly he was unable to maintain good form in back-to-back stages, winning one and then losing a bunch in the next.
Then a sudden, temporary metamorphosis occurred in the three consecutive tours. We all know, how it ended.
Marco Pantani probably holds the world record for the number of times a cyclist was caught for doping offenses; 3 suspensions during his career and twice after death. The post-mortem examination showed illegal substances in his system. In the Operacion Puerto, he was found to have been prescribed twice as much doping as others, who received 2-year suspensions. Moreover, he used cocaine. Remember, what happened to Ullrich and Boonen when they were caught using recreational drugs outside competition?
He was one of the 2 racers caught in possesson of illegal substances during the all-out search during a Giro. The other one, Dario Frigo, was called "scum" by the cycling world, while Pantani remained a hero. Despite all this, he never admitted cheating.
His record achievements at the Alp d'Huez don't mean much. One can concentrate on this one climb, saving energy during this and the previous stages and start an all-out effort from the point at which the time starts running. It's diffferent to cover the last ascent after a 200 km solo ride with 6 intermediate climbs from racing only during the last ascent, catching up with the others who attacked earlier.
How about his virtues other than cheating, limited capabilities and meager palmares?
He must be found guilty of one of the most heinous offenses a cyclist can commit. While riding in a Giro, on the deciding, most difficult mountain stage, he kept charging on the climbs, leaving his team leader, Garzelli, exposed to the attacks by his rivals for the overall title, theoretically better climbers, Casagrande and Simoni, thus putting in peril his teammate's chances for the overall vioctory for the sake his own stage triumph. While Simoni was able to keep pace with Pantani, other racers were poking jokes at Garzelli on account of his 'loyal' domestique. Luckily for Garzelli, the stage ended with a long descent, the three contenders regrouped and crossed the finish line together. Eventually, Garzelli claimed the overall victory during the ITT. Pantani, meanwhile, despite being seemingly the strongest on the day when he abandoned his comrade, failed to win the stage; one more proof of his lack of stamina. After the race, Garzelli thanked Pantani for helping him in achieving the overall victory. Was it sarcasm or was he blinded by the cult of his domestique? Pantani was consistently dropped early during that Giro, except for the stage he tired to win. Even in the mountainous ITT, which directly followed, he finished somewhere outside the top 30. Despite his superb stamina, the poor chap must have been tired after the previous day's effort, plus the ITT was over 30 km long.
Let's not forget Pantani's other talents. After all, he proved to be a cemedian and a prima donna. After a fall at a slow speed up an ascent, in which a number of others also 'suffered', he was the only one that didn't immediately get back on the bike, but sat down at the roadside making tragic faces to the camera for a couple of minutes. He was at this point outside the contention for the top 10 overall and didn't suffer during the fall in the least. After the Giro he demanded to be included in the Tour, evidently as the only competent person to 'check out how good Lance Armstrong really is', as he put it. He just had checked Dariusz Baranowski to find out that he is slightly better than himself, finishing the Giro 12th and 13th, respectively.
After the Mount Ventoux stage, where Armstrong stopped pedaling on the last uphill meters, allowing Pantani to win, at the post-stage press conference the victor declared simply that he won on account of being better racer than Lance.
When he lost his first Giro to Berzin, being in the meantime the virtual leader, some commentators pointedly explained, that he made a mistake by slowing down. Had I not made such mistakes, I would have beaten Eddy Merckx.