If you're watching the Mike Tyson documentary, The Knockout, then you've probably learned more about the professional boxer than you ever thought you would. Including the fact that there were a lot of people in life who he credits for his success. One of those people is Jim Jacobs, a handballer who managed Mike Tyson when he was 18 and becoming one of the most famous boxers in the U.S.What to know about Jim Jacobs and Mike Tyson.It is believed that Mike Tyson saw Jim Jacobs, his manager, as a father-figure. While Cus D'Amato trained Mike (and was certainly more well-known), Jim taught Mike everything there was to know about boxing history, and was one of the key figures who made Mike go from great to unbeatable. It's said that Jim hid his leukemia diagnosis from Mike, so Mike was even more devastated when Jim passed away in 1988.Getting to know Jim Jacobs, handballer legend.While Jim Jacobs isn't exactly a household name, he's still one of the most influential people in boxing history. When he was 17, Jim started collecting films of boxing matches. He essentially became a boxing scholar, and was trained by D'Amato himself. The two became friends, and this is how Jim later became Mike's manager. In 1959, Jim went into business with Bill Clayton, and the two came to own production companies The Greatest Fights of the Century and Big Fights Inc.In 1966, Sports Illustrated claimed, ″There is no athlete in the world who dominates his sport with the supremacy that Jimmy Jacobs of Los Angeles and New York enjoys in four-wall handball."Jim and Bill began managing boxing champs, including Edwin Rosario and Wilfred Benitez. Jim managed Mike up until his death in 1988. He had leukemia, but officially died of pneumonia at Mount Sinai Hospital, according to AP. ″He had suffered from chronic lymphocytic leukemia for nine years,″ Bill stated.Unfortunately, many believe that Jim's death ultimately led to Mike's eventual downfall. "The Cus thing he dealt with, he made history which will NEVER be surpassed. IMHO once Jim Jacobs passed away that was the beginning of the end," someone tweeted.Another claims "if @MikeTyson's mentor didn't pass away and his 2nd coach Jim jacobs he [would have] reigned longer than he did."Posthumously, Jim was recognized on a grander scale when he was inducted into the International Boxing Hall of Fame, the World Boxing Hall of Fame, the International Jewish Sports Hall of Fame, as well as the U.S. Handball Hall of Fame. And in 1990 he was inducted into the Southern California Jewish Sports Hall of Fame.And, fun fact: Jim was a major comic book collector. People believe he has a warehouse in Los Angeles that contains over 880,000 comic books. Unfortunately, nobody knows where that warehouse is.Watch the second part of Mike Tyson: The Knockout tonight on ABC at 8 p.m. EST.