From 1980 to 2010:
1st round: 66 QBs selected. Only 8 didn't start at least 1 season. 10 started only 1 season. This group represent 94 total pro bowl berths.
2nd round: 31 QBs selected. 11 didn't start at least 1 season. 5 only started 1 season. They represent 31 pro bowl berths and include Bret Favre, Drew Brees, Randall Cunningham, Boomer Esiason.
3rd round: 36 QBs selected. 19 never started a season. 5 only started 1. Only 9 pro bowls in this group which includes Chris Chandler, Matt Schaub, Jay Schroeder, Neil O'Donnell, Jeff Hostetler, and Brian Griese.
4th round: 48 QBs selected. 34 never started a season. 4 only started 1. Only 6 pro bowls in this group which includes Rich Gannon, Steve Beuerlein, Aaron Brooks and David Garrard.
5th round: 32 QBs selected. 26 never started a season. 2 only started 1. Only 1 guy started more than 2 and that was Mark Brunell who also accounts for the 3 pro bowls of this group.
6th round: 60 QBs selected. 42 never started a season. 6 only started 1. But there were an amazing number of multi year starters in this group. There were 19 pro bowl seasons headed by (of course) Tom Brady but also including Matt Hasselbeck, Jeff Blake, Marc Bulger, Mark Rypien, Stan Humphries, Rodney Peete, Steve Bono, John Friesz and Derek Anderson.
7th round: 51 QBs selected. 46 never started a season. 3 only started 1. Matt Cassel and Gus Frerotte went to Pro Bowls and along with Ryan Fitzpatrick are the only multi-year starters.
8th round+: 97 QBs selected. Most of these guys of course, never saw anything. But there were some successful QBs in this group including Trent Green, Wade Wilson, Elvis Grbac, Brad Johnson, Doug Flutie, and Don Majkowski. 8 pro bowl berths.