Falk could be at Cornell right now and his Wonderlic will probably come in higher than any other WSU QB than Bledsoe who was Ivy League smart. Graham Harrell scored relatively low....but not nearly as low as Bradshaw, Kelly and Marino at 15. I don't know how much higher intelligence really benefits a QB and his decision making.
http://www.nflstatanalysis.net/2011/03/qb-wonderlic-scores.html
I would suggest that your question is answered pretty easily simply by looking at QBs with the highest scores, and asking how many of them turned into good QBs.
Top 5 scorers: Ryan Fitzpatrick, Greg McElroy, Jason Maas, Blaine Gabbert, Drew Henson. Fitzpatrick was the most successful of them, and has cobbled together a decent career as a journeyman, but he'll never be mentioned for the HOF.
You have to get to Eli Manning at #10 to find someone who might be an HOF candidate. He scored a 39. So did Todd Husak and Brian Griese...neither of whom will be in the hall, or could even make it as a regular starter.
Bledsoe got a 36. So did Jared Zabransky. Compare their pro careers.
Aaron Rogers, arguably the best QB in the NFL today, got a 35. So did Christian Ponder, Matt Leinart, Kellen Clemens, and Drew Stanton.
Tom Brady and Steve Young got 33s. So did Charlie Whitehurst. Matt Ryan and Joey Harrington got 32s.
John Elway and Troy Aikman got 29s. So did Rex Grossman and Brady Quinn.
Drew Brees and Peyton Manning got 28s, just like Kevin Kolb and Brooks Bollinger.
Jason Gesser, Ryan Leaf, and Alex Brink all got 27s. So did Rich Gannon and Joe Flacco.
Carson Palmer and Jay Cutler scored 26...same as Akili SMith.
Brett Favre and Tim Tebow both got 22.
Steve McNair, Randall Cunningham, Jim Kelly, Dan Marino, and Terry Bradshaw all got 15s. So did Vince Young. Off the top of my head, I think there's 10 Super Bowl starters in that first group.
Donovan McNabb, Charlie Batch, and Kordell Stewart got 14s. Neil O'Donnell got 13. Jeff George got a 10. All of them had decent careers. There's at least a couple more Super Bowls among them.
Bottom line - the Wonderlic is no more predictive of QB success than the SAT is of college success. It's just one more quantifiable piece for front office evaluators to look at.