Here's a look at some statistics detailing the success of late round QBs from 1994-2013.
http://www.footballoutsiders.com/stat-analysis/2014/nfl-draft-round-round-quarterback-data
3rd round
You'd figure that over two decades you could find some pretty good prospects that came out of the 3rd round but Schaub and Wilson are the only guys to appear as long-term starters. Wilson himself largely fell due to his height and not questions about his ability as a QB. Mel Kiper stated that he'd have been a top 10 pick if he were about four inches taller so its pretty safe to say that he's more the exception and not the rule.
Wilson is the only quarterback since 1978 to be drafted after the second round and start all 16 games in his rookie year. Based on how well he's played so far, there's no reason not to believe Wilson will go down as the best third-round quarterback since Joe Montana (1979).
The Good-
Russell Wilson
Matt Schaub
Nick Foles
Brian Griese
The Bad-
Andrew Walter
Dave Ragone
Charlie Whitehurst
Jonathan Quinn
Brock Huard
Trent Edwards
Chris Simms
Charlie Frye
Brodie Croyle
Stoney Case
Bobby Hoying
Eric Zeier
Colt McCoy
David Greene
Giovanni Carmazzi

Ryan Mallett
Kevin O'Connell
4th Round
Not much to speak of here. Cousins has been coming on and improving so that's good, but otherwise its a pretty weak group outside of Garrard, Orton, Brooks and Cousins.
http://www.footballoutsiders.com/stat-analysis/2014/nfl-draft-round-round-quarterback-data
Last year I wrote that David Garrard was the best fourth-round quarterback since Rich Gannon (1987). Obviously there's not much competition for that title. Aaron Brooks and Kyle Orton could put up some numbers, but would make baffling mistakes as well. Orton may have never caught on in Chicago if Grossman wasn't so brittle.
The Good
David Garrard
Kyle Orton
Aaron Brooks
Kirk Cousins
Dak Prescott
The Bad
Danny Kanell
Rob Johnson
Tyler Wilson
Stefan LeFors
Seneca Wallace
Pat Barnes
Matt Barkley
Rohan Davey
Sage Rosenfels
Stephen McGee
Chad May
Luke McCown
Steve Stenstrom
Chris Weinke
Mike Kafka
Dave Barr
Danny Wuerffel
Jesse Palmer
Joe Germaine
Jeff Lewis
Doug Nussmeier
Perry Klei
5th Round
The Good



The Bad

AJ Feeley
John Skelton
Mike McMahon
Troy Smith
Josh Johnson
TJ Yates
Craig Krenzel
Kurt Kittner
Dennis Dixon
Craig Nall
Randy Fasani
Brian St Pierre
Tee Martin
Ingle Martin
Adrian McPherson
Brandon Doman
Erik Ainge
Jay Barker
Jeff Rowe
John David Booty
Jonathan Crompton
Kevin Daft
Nate Davis
Nathan Enderle
Omar Jacobs
Rhett Bomar
Ricky "Montana" Stanzi
6th Round
I think when people usually talk about finding a QB in the draft, this is the round that defines that, with everyone hoping that they can get the next Brady or even a Matt Hasselbeck or Marc Bulger.
The Good
Tom Brady
Matt Hasselbeck
Marc Bulger
Tyrod Taylor(for now)
Derek Anderson(With "good" being relative here I guess)
The Bad

Andre Woodson
Jim Sorgi
Jim Miller
Andy Hall
Joe Webb
Chuck Clements
Brooks Bollinger
Colt Brennan
Bruce Gradkowski
Dan LeFevour
Craig Whelihan
JaJuan Seider
Curtis Painter
Jeff Smoker
Tony Pike
Jerry Colquitt
J.T. O'Sullivan
John Dutton
Josh Booty
Ryan Lindley
Josh Harris
Keith Null
Josh Heupel
Rusty Smith
Mike Cawley
Spergon Wynn
Mike Teel
Jordan Palmer
Spence Fischer
Tom Brandstater
Todd Husak
Drew Henson
Kliff Kingsbury
Mike Cherry

7th Round
The word "good" here starts to become very loosely applied.
The Good
Matt Cassel
Ryan Fitzpatrick
Matt Flynn
Tim Rattay
Koy Detmer
Gus Frerotte
The Bad
Casey Bramlet
Glenn Foley
Zac Dysert
D.J. Shockley
Tony Graziani
Chandler Harnish
James Kilian
Ken Dorsey
Brad Sorensen
Jeff Kelly
Matt Mauck
John Walsh
Moses Moreno
Jon Stark
Jarious Jackson
Kyle Wachholtz
Greg McElroy
Ronnie McAda
Gibran Hamdan
Sean Canfield
Chris Greisen
Seth Burford
John Navarre
Tony Corbin
Levi Brown
Wes Pate
Bradlee Van Pelt
Zac Robinson
Scott Covington
Jay Walker
Cody Pickett
Steve Matthews
Wally Richardson
Michael Bishop
Joe Hamilton
Tyler Thigpen
Alex Brink
The BJ's
BJ Coleman
BJ Daniels
BJ Symons
But history suggests that that quarterback taken on Day 3 will, on average, play two NFL seasons, never be his team's primary starter, will sport a 2-5 career record (if he's lucky), complete 54.7 percent of his passes and throw 3 touchdowns against 6 interceptions.
http://www.cbssports.com/nfl/eye-on-football/24563457/excited-about-that-late-round-qb-your-team-drafted-dont-be
Its fun to look for QB's late in the draft, hoping that one might turn out to be a diamond in the rough but history shows that you're far more likely to wind up with a huge chunk of coal.
For future drafts, Wilson may have broken the height discrimination against quarterbacks, but history still shows he will be an outlier. It's true you can get a quarterback later in the draft, but he's more likely to turn out to be Curtis Painter, Mike McMahon, B.J. Symons or that guy from The Bachelor than the next Wilson or Brady. If you want a franchise quarterback, the top of the draft is still the first place to look.