Joe Horn
Before Andy Reid arrived in Kansas City, the offensive memories for Chiefs Kingdom weren't all that plentiful. That's why the arrival of Joe Montana and the years of Trent Green are held in such high esteem because for very long stretches of f ffbff, the Chiefs were among the most forgettable offenses in the league (e.g. the entire '80s and then some).
Part of that was due to the lack of playmakers over the years. Yes, everything starts with a quarterback, but it doesn't help if he has no one to throw to, and the Chiefs really missed a big opportunity when one was needed when they didn't allow Joe Horn to mature on the roster.
Horn is known as one of the greatest wide receivers in New Orleans Saints history but he was originally a fifth-round pick of the Chiefs back in the 1996 NFL Draft. Horn was actually playing for a Memphis-based franchise in the Canadian Football League (yes, the CFL tried American expansion for a spell), and Horn was a sensation in 1995 with more than 1,400 receiving yards to his credit.
The Chiefs were intrigued by what Horn could do in the NFL but they never leaned on him enough to properly see just how high his ceiling might go. In four seasons in Kansas City, Horn only had 53 catches for 879 yards. In free agency, the Saints came calling with a 5-year, $14M deal, and in his first season in the Big Easy, Hornd turned in career highs in his very first year including catches (94), receiving yards (1,340) and touchdowns (8).
Horn would go on to make four of the next five Pro Bowls as one of the league's best wide receivers, and he was eventually inducted into the Saints Hall of Fame. It's frustrating that the Chiefs couldn't hold on because they could have used him. Instead of Snoop Minnis leading the franchise in receiving yards, for example, in 2001, it could have been someone a bit more productive.