As a smoker, I've seen guys who smoke be able to keep up with other athletes in short bursts. I've done it myself playing cricket to a fairly good standard(DIV 1). Division 1 cricket is 2 steps below pro in the UK, you have division 1, premier and then county level, which is pro and then the top level which is international(but these players all compete in county and premier level as well - Premier is spread out so each county has a premier league and county players are assigned to a team). There is something you learn though over the years, some people are just better, they are naturally faster, stronger, run longer, etc, and there is no real reason for it. It is not unbelievable that someone who is genetically gifted like Joe, could smoke and reduce his lung size(we don't know how long he has smoked for or at what intensity) , but still competed at a top level in kickboxing, where there are just 3, 3 minute rounds. It is not like a boxing, which is an endurance test, it is more reminiscent of a sprint.
He first said that it was occasionally, but the more he talked he said he does it regularly. He even said that he smoked between fights in the tournament. I'm pretty far behind on JRE, but I moved this one up to the top. Schilling seemed like a very good down to earth dude. I like him, despite the fact he knocked out Manheof.