Much has been made out of the correlation to success inherent in higher draft picks. I think the current number is 52% success rate with the #1 overall pick? And that's with picking any player at any position? Well, let's take a look at quarterbacks anyways since that's what that correlation has been used to advocate drafting.
I decided to look at the current starting quarterbacks in the NFL. This automatically disqualifies Christian Ponder, Blaine Gabbert, Josh Freeman, Jake Locker and RG3. It also disqualifies Josh McCown and Sam Bradford.
Ten out of 32 current starting quarterbacks were drafted in the top 10 overall with 7 of those 10 being drafted #1 overall. Here's the guys drafted in the top 10:
Carson Palmer- #1 in 2003
Matt Ryan- #3 in 2008
Cam Newton- #1 in 2011
Peyton Manning- #1 in 1998
Matthew Stafford- #1 in 2009
Andrew Luck- #1 in 2012
Alex Smith- #1 in 2005
Ryan Tannehill- #8 in 2012
Eli Manning- #1 in 2004
Phillip Rivers- #4 in 2004
Out of those 10 quarterbacks: five of them are no longer with the team that drafted them. That's a 50% success rate on the surface of it but when you consider that three more have been in the league for less than three full seasons...in fact only Matthew Stafford and Matt Ryan have both been in the league longer than their rookie deals and still play for the teams that drafted them. Eli and Rivers famously got traded straight up in 2004 when the Chargers drafted Eli and he refused to play for them. Nothing like spending the #1 pick to get the guy who was drafted #4 overall right?
And seven more current starters were taken at all in the first round...eight if you count Aaron Rodgers. The rest are:
Joe Flacco- #18 in 2008
EJ Manuel- #16 in 2013
Jay Cutler- #11 in 2006
Jason Campbell- #25 in 2005
Drew Brees- #32 in 2001 It was pointed out in the comments that Brees was actually a second round pick. As in there were less than 32 teams back then.
Ben Roethlisberger- #11 in 2004
If you prefer to count Rodgers then he was drafted #27th overall in 2005.
That's 17 current starters that were drafted in the first round-these guys have a combined 7 Super Bowl rings and only 5 of them won it with the team that drafted them. That means that a first round quarterback that you draft has less than a 33% chance of winning the Super Bowl for you before you give up on him. Although, to be honest there is only one other quarterback currently in the NFL who has won the Super Bowl: Tom Brady-who was famously taken in the sixth round and was the seventh quarterback drafted that year. And, we all know that he's got three rings while Roethlisberger and Eli have 2 apiece.
Not to mention that, of the 17 current first round starters, Ten are still with the team that drafted them with four of those quarterbacks having been in the NFL for less than 3 full seasons. Which means that those four are still on their rookie deals and haven't had a chance to go anywhere else. So that's another 33% chance that the guy you draft will choose to stay after his rookie deal is up.
To conclude this: simply because you use a top-10 pick on a quarterback doesn't guarantee at all that he will start for you past his rookie contract. Not having him as the starter past his rookie contract is a pretty clear indicator of a bust. With those odds, why would anybody advocate tanking-much less tanking for an underclassman that could easily return to college?