Whitaker and McCall? I am not certain, I know Whitaker snorted coke towards the tail end of his career, and still did ok. McCall I know took heroin, probably other things, but I am not sure exactly when. I heard that the bizarre Lewis fight where he had a breakdown had a lot to do with coming off drugs, but that is hardly a successful example. If you count cigarettes, which I think you definitely should, Mayorga and Monzon are the definitely choices. Especially Monzon, the man was a machine. His lungs must have been ****ed but I dont think I have ever seen him break a sweat.
Tim witherspoon was fined for testing posative to smoking weed while wba champion and later crawled out of a toilet window to avoid a drugs test in london.
Walker smoked two packs a day, but I think Nicotino Roacche definitely takes the cake here. Nicotino actually took drags between rounds, a habit discretely hidden by his corner men behind a strategically held towel. His death at 66 was certainly hastened drastically by his nicotine addiction. Pinklon Thomas was famous for kicking a heroine addiction, but considering how insidious that is, maybe he relapsed at some time during his career.
The obvious one is Tyson, word I have is he used a lot of drugs but is still considered an all time great, it did affect his career
Prenell Whitaker was coke addict while he was still the best boxer in the world. Nicclonio Locche was a heavy smoker and drinker. Ledgend is that he not only smoked between rounds but also drank wine. Mando Ramos was a heavy drinker. Ricardo Mayorga smoks cigritts. To be honest It would not surprise me to learn that a lot of high leval boxers as well as athletes from other sports Drink, Smoke Cigritts or Pot more than we might think they do.
Pinklon Thomas fought for a while while back on smack but it showed up vs Berbick, he was slow and lethargic
Mike Ayala shot up heroin before a few big fights, he claimed. Not the best drug to fight on, I would guess. But I suppose if you are a hardened addict it's doable.
Benny Lynch was a chronic alcoholic even during his fighting heyday before succumbing to the disease at 33 years of age.