2. Ryan Leaf, San Diego Chargers (No. 2, 1998)
It's not just that Leaf was historically inept (14/36 TD/INT ratio), it's that his failure led the team to drafting Drew Brees, which led the team to drafting Philip Rivers, which led to them starting Brees anyway, which led to one playoff year, an injury and a trade, which leads to the team starting all over again with Rivers and hoping he pans out. Meanwhile, the Chargers have essentially wasted the first five years of the great LaDainian Tomlinson's career with just one playoffs year. By the time (if) Rivers matures, it's quite likely L.T. will start declining. Thank you, Ryan Leaf, thank you for destroying a franchise.