Everyone believes that it is easy and far cheaper to draft a quarterback in round four, five, or six. That is after all where the Patriots found Tom Brady. The fact is that most quarterbacks do not find that kind of success or even half of that success in the NFL.
Since 2001, 47 quarterbacks have drafted in the first round of the NFL Draft. 42 quarterbacks have been taken in that same timeframe in rounds two and three. Finally 122 quarterbacks have been drafted in rounds four through seven. That is a lot of quarterbacks to fill the rosters of 32 teams.