Consistancy is key in the NFL, as players and teams look to maintain success over a prolonged period of time.Tom Brady was the ultimate "Mr. Consistant," going down as the best player in history after playing for over 20 years at an elite level in the NFL.However, there are many more examples of quarterbacks who were a "flash in the pan," and never had more than one year of success in the league.5 biggest one-year wonder quarterbacks in NFL history#5 - Steve Beuerlein, Carolina PanthersSteve Beuerlein with the Carolina PanthersSteve Beuerlein was a quintessential journeyman quarterback back in the 1990s, playing for six teams in a career that lasted 17 seasons.Beuerlein was seen as a backup throughout the majority of his career, but excelled with the Carolina Panthers in 1999. Beuerlein had 36 touchdown passes and 4,436 yards — both of which remain Panthers franchise records to this day.This was the only season in Beuerlein's career he threw for more than 20 touchdowns, as he was named to the Pro Bowl for his sole appearance.#4 - Mark Rypien, Washington RedskinsMark Rypien with the Washington RedskinsWashington Redskins QB Mark Rypien had spent much of his career backing up Joe Thiesmann, as injuries plagued the early part of his career.However, in 1991 he got his chance, and boy did he take it. Rypien passed for 28 touchdowns with a QBR of 97.1 as he helped Washington go 14-2. Not only that, he led the Redskins to Super Bowl glory that year, as he took home Super Bowl MVP.Rypien would never reach those dizzying height again, langushing back into mediocrity as injuries once again hindered his progress.