Interesting analysis. Not sure I agree that Goff is a bust after just one season and it's premature for Gabbert too. They are also on teams that I'm not sure even Brady could help all that much. I also think it would have been more fair to bracket them as Elite, Good, OK, Bust. Guys like Rivers, Palmer, Stafford are a lot more than just "OK" quarterbacks. Sanchez was OK, he did have 4 road playoff wins. I think you missed Ben (Elite) in your list - he was almost top 10.
On the flip side of your argument, how many elite QBs other than Brady have been drafted late?
Sure, I'm not claiming to have made the definitive list of QBs and where they stand, it was more illustrative. The premise the post was based on the idea of another poster that we needed a Top 10 pick to get a Brady replacement QB.
I'd say Gabbert's a bust, and while I was being a bit negative on Goff, usually we'd have seen something from a guy drafted 1st overall whereas all reports were that he couldn't do much even on the practice field. But if you want to put them as TBD, that's fine from my point of view. That would make it 4 Elite, 6 Okay, 11 Busts and 5 TBDs out of 26 guys, a split of 15%/23%/42%/19%.
I disagree though that Rivers/Palmer/Stafford are "Good" QBs; every time they've faced the pressure of winning a big game, even when they've had the tools to do so, they've choked big time and lost it with terrible play, usually with egregious interceptions they had no business throwing. Not as in "didn't play well enough", as in "we'd have had a better chance to win if they got in a car crash on the way to the stadium". In fact, that's why they belong with Sanchez as "Okay" guys, Sanchez was an okay QB and at least could game manage enough to win a game with a great defense on occasion. When you needed more, he didn't have it. And sure, I'd have put Ben as "Elite" but he wasn't Top 10 so didn't come into consideration.
As to Elite QBs drafted outside of the First Round, here's the guys who actually managed to start at least 10 games at QB in the NFL (for consistency I'll keep my previous rating system and will make unjustified snap judgements on very young players and call late round guys who can't stick busts):
Dak Prescott (Elite)
Trevor Siemien (Okay)
Zach Mettenberger (Bust)
Gee?-no! Smith (Bust)
Mike Glennon (Okay)
Brock Osweiler (Bust)
Russell Wilson (Elite)
Nick Foles (Okay)
Kirk Cousins (Okay)
Andy Dalton (Okay)
Colin Kaepernick (Okay)
Tyrod Taylor (Okay)
Jimmy Clausen (Bust)
Colt McCoy (Bust)
John Skelton (Bust)
Chad Henne (Bust)
Kevin Kolb (Bust)
Drew Stanton (Bust)
Trent Edwards (Bust)
Tyler Thigpen (Bust)
Kellen Clemens (Bust)
Tarvaris Jackson (Bust)
Bruce Gradkowski (Bust)
Charlie Frye (Bust)
Kyle Orton (Okay)
Dan Orlovsky (Bust)
Derek Anderson (Bust)
Matt Cassell (Okay)
Ryan Fitzpatrick (Okay)
Matt Schaub (Okay)
Luke McCown (Bust)
Chris Simms (Bust)
Seneca Wallace (Bust)
Josh McCown (Okay)
David Garrard (Bust)
Drew Brees (Elite)
Chris Weinke (Bust)
Sage Rosenfels (Bust)
AJ Feeley (Bust)
Counting that up, we get 3 Elite Guys (Prescott, Wilson, Brees), 12 Okay guys and 24 Busts out of 39 guys, a split of 8%/31%/62%. There's around 1.5 of these late round guys who played at least 10 games to every guy drafted in the Top Ten.
So you CAN get almost as many Elite guys outside of the first round as you can Top 10. On the other hand, as pointed out by several people, you can get probably a similar breakout from the first round as a whole, rather than just considering the Top Ten hence you'll end up with significantly more Elite guys if you consider the First Round rather than Top 10. So obviously there's a much higher likelihood of finding an Elite guy in the first round, but not so obviously there's not so much of an incremental benefit in getting to the top of the 1st round because QB is more of a crapshoot than other positions.
Now my non-First Round list doesn't include the majority of drafted QBs, the vast majority of whom never even made a roster, so never played 10 games and were obviously "busts". On the other hand, if you take draft value in points and look at pick expenditures, I'm guessing there's not a major difference in investment in 5-7x as many later round QBs as there is in a single high First Round draft pick. That would be probably the most interesting analysis, draft pick point values versus QB starters/backups/elite/busts and where the value sweet spot is. Just looking at the Patriots, one would guess "Second Round" is where that metric hits max efficiency.