9. Rick Mirer
Mirer had a great rookie season as he set all kinds of records that stood until Peyton Manning came along. However, he suffered a sophomore slump to turned into a career meltdown. The 1993 Offensive Rookie of the Year was a total letdown for the Seattle Seahawks.
In short, his passing numbers dropped by 700 yards while his overall completion rate stood at barely above 50%. Those are some miserable statistics and show how rubbish he was in his second year. Unfortunately, Mirer never lived up to the potential of his rookie season.