I guess it's tough to split hairs when we're talking the worst, but there's some bullshit on that list.
Brandon Weedon was worse for the Browns than Tim Couch? Elvis Grbac was worse in his one year with the Ravens (where they actually went to the playoffs) than Kyle Boller who got drafted because he could throw a ball through the uprights while on one knee? Neil O'Donnell worse Steelers quarterback? They went to a Super Bowl with him as the starter.
You won't get me to cape for Tim Tebow but I don't think he was any worse than Tommy Maddox who was drafted (in the 1st round) to replace Elway while Elway was still in his prime!
And Donovan McNabb honorable mention for worse Vikings QB? Kiss my ass.