the numbers say that chances are after the first round, a pick on a qb is basically throwing it in the garbage.
Actually, the numbers really say that a pick on a QB, period, is usually throwing it in the garbage. But let's look at 1st round QBs.
Since Peyton Manning was picked, here are the QBs taken in the 1st round:
98: R. Leaf (epic bust)
99: T. Couch (bust)
99: D. McNabb (multiple Pro Bowls)
99: Akili Smith (bust)
99: D. Culpepper (traded in what should have been his prime)
99: C. McNown (bust)
00: C. Pennington (above average)
01: M. Vick (cut in what should have been his prime)
02: D. Carr (bust)
02: J. Harrington (bust)
02: P. Ramsey (bust)
02: C. Palmer (multiple Pro Bowls)
03: B. Leftwich (mediocre)
03: K. Boller (bust)
03: R. Grossman (mediocre)
04: E. Manning (?)
04: P. Rivers (multiple Pro Bowls)
04: B. Roethlisberger (franchise-quality)
04: J. Losman (bust)
05: Alex Smith (bust)
05: A. Rodgers (elite)
05: J. Campbell (mediocre)
06: V. Young (cut in what should have been his prime)
06: M. Leinart (bust)
06: J. Cutler (traded in what should have been his prime)
07: J. Russell (epic bust)
07: B. Quinn (bust)
08: M. Ryan (franchise quality)
08: J. Flacco (above average)
09: M. Stafford (above average)
09: M. Sanchez (mediocre)
09: J. Freeman (above average)
(excluding '10 and '11 because more time is needed to evaluate)
So of the last 32 first-round QBs selected, exactly 3 have started a Super Bowl and won, and approximately 7-8 teams (including the aforementioned 3) got a good return on their investment.