I mean, when you list the best QBs of the last 40 years, many(most?) were taken outside the top 10.
Peyton Manning, Andrew Luck, Cam Newton, Joe Burrow, Matthew Stafford, Eli Manning, Carson Palmer, David Carr, Drew Bledsoe, and Troy Aikman were all #1 overall picks, and that's just back to 1989. There were also some dogs in there, who I won't bother listing.
My rough read on draft picks over the last 20 years indicates that a high first round pick has a 50% chance of being a steady starter for a number of years. As you move down the rounds, the percentage drops. Tom Brady was a 6th round pick, but if you count up the number of 6th round quarterbacks that were steady starters, it's pretty low.
But that figure gives you a measure of one reasonable floor. If the floor you're looking for is All-pro level with a record well over 0.500, the numbers start lower, and still drop off as you move down the rounds.
All of that is meaningless in the most important sense. What matters is will the guy we picked pan out, and how much did we pay to get him. Jaguars are paying just their first this year to get Lawrence. Niners paid 3 firsts and more to get whomever they take. We'll know in 5-8 years how it shakes out.
