What makes a good (or bad) NFL quarterback? If the answers were easy, NFL teams wouldn't constantly make mistakes at the top of the draft. Sometimes you can blame the system, sometimes the NFL team, sometimes the coaching the player gets, sometimes the talent around them. There are no certainties.

One useful statistic, it seems, is completion percentage in the final year of college. Many quarterbacks who display lesser accuracy in college never get that corrected in the NFL. There are exceptions (Matt Ryan, for example, was under 60 percent completions at Boston College), but a whole lot of those guys go bust in the NFL.

The table below shows college quarterbacks drafted in the first round over the last 20 years, sorted by completion percentage their final year of college. There have certainly been some busts near the top of that list, but the quarterbacks at the bottom have almost entirely flopped, and quickly.

The two quarterbacks who will be drafted in the first round this Thursday, Jameis Winston and Marcus Mariota, both rank favorably in this area.

COMPLETION %, FIRST-ROUND QUARTERBACKS, 1994-2015
YearPkPlayerAttComPctP Yds
199911Daunte Culpepper40229673.63690
201222Brandon Weeden56440872.34727
19991Tim Couch55340072.34275
20044Philip Rivers48334872.04491
20122Robert Griffin III40629171.74293
20121Andrew Luck40428871.33517
201432Teddy Bridgewater42730371.03970
201422Johnny Manziel42930069.94114
200525Jason Campbell27018869.62700
200411Ben Roethlisberger49534269.14486
2015?Marcus Mariota44530468.34454
201316EJ Manuel38726368.03397
20071JaMarcus Russell34223267.83129
201025Tim Tebow31421367.82895
20143Blake Bortles38225967.83581
20051Alex Smith31721467.52952
200018Chad Pennington43329267.44006
20037Byron Leftwich49133167.44268
19955Kerry Collins26417666.72679
200524Aaron Rodgers31620966.12566
20111Cam Newton28018566.12854
20095Mark Sanchez36624165.83207
200610Matt Leinart43128365.73815
2015?Jameis Winston46730565.33907
20063Vince Young32521265.23036
20021David Carr47630864.74299
19943Heath Shuler28518464.62354
19946Trent Dilfer40025563.83799
200818Joe Flacco52133163.54263
201110Blaine Gabbert47530163.43186
20031Carson Palmer48930963.23942
19992Donovan McNabb25115762.52134
20041Eli Manning44127562.43600
200722Brady Quinn46728961.93426
20128Ryan Tannehill53132761.63744
201112Christian Ponder29918461.52044
20091Matthew Stafford38323561.43459
19981Peyton Manning47728760.23819
200422J.P. Losman42225159.53077
20083Matt Ryan65438859.34507
200611Jay Cutler46227359.13073
19993Akili Smith32519158.83307
200917Josh Freeman38222458.62945
199912Cade McNown32318858.23130
20023Joey Harrington32218657.82415
19953Steve McNair53030457.44863
200322Rex Grossman50328757.13402
200232Patrick Ramsey44925657.02935
199726Jim Druckenmiller25014256.82070
20101Sam Bradford693956.5562
19982Ryan Leaf37521056.03637
20118Jake Locker33218455.42265
20011Michael Vick1618754.01234
200319Kyle Boller42122553.42815

--Andy Richardson