Revis was a great pick at #14. How many DBs on thelist did we pick in the top 15? The answer is zero. We traded picks and drafted a bunch of predominantly low second, third and fourth picks. Outside of Samuel, who we certainly did help become a top CB, mostly by scouting his ability, out of the 4th, we had a lot of injuries and mediocre players, using mediocre picks.
Again, I don't think you get top cornerbacks consistently and you certainly don't build them out of clay. You need to either risk a very high pick, on a guy that could still be injured or fail, or you use the shotgun approach.
We drafted very low to get McCourty and converted him into one of the top safeties and got big bang clock hoping he'd develop a brain, so that's 50/50 on low round firsts and a bunch of crap shots.
I'm really surprise that Bedard thinks you can develop cornerbacks. It's really a position we're they're more born than made, which is probably why they've gambled on injured ones. Without risking a high first round pick (which still bust at this position) we don't have or trading our whole draft for one, you get players who either don't have the athletic ability at the position it's most crucial, or have attitude, injury or other concerns.
A third round pick with athletic ability, character, drive, smarts etc. is a 1st round pick. It's like drafting a bunch of outfielders hoping one becomes a shortstop. Not a learned skill.
I decided to look at the top 10 teams (hooray power-rankings) in the league's depth charts and chart where their top 2 CB's were drafted, if at all, to test your hypothesis (as I understand it, via the bolded language above):
Bonus - #1 Pass Defense (Yards Allowed) = Kansas City:
Parker UDFA ; Smith 2nd round
10. Miami:
Grimes Undrafted; Finnegan 7th round
9. Detroit
Mathis 2nd round; Slay 2nd round
8. Dallas
Carr 5th round; Scandrick 5th round
7. Arizona
Peterson 1st round; Cromartie 1st round
6. Indy
Davis 1st round; Toler 4th round
5. Seattle
Sherman 5th round; Maxwell 6th round
4. Philly
Williams 7th round; Fletcher 3rd round
3. Denver
Talib 1st round; Harris UDFA
2. New England
Browner UDFA ; Revis 1st round
1. Green Bay
Shields UDFA; Williams UDFA
Clearly, there's minimal, if any, correlation between playing winning football and relying on CB's drafted early. Looks to me like there are coaches out there who can take UDFA's and help them become starters for teams who will play in the playoffs and win Superbowls.
Obviously this isn't the end-all, most elaborate analysis of this topic possible, but I think it's enough to defeat the notion that the Patriots coaches' role shouldn't be questioned for not developing CB's since they didn't draft them high in the 1st round.