SB Nation has a ton of really strong and entertaining writers and Jon Bois is towards the top of that list. He decided to provide a breakdown of teams and their draft success in the middle portion of the past decade. Some of his conclusions are obvious (the Lions were terrible at drafting), while others are interesting (tight ends had some of the greatest success rate over that time).
He compared Lions GM Matt Millen and his draft picks to a dart board. Like, Bois made a list of available players to the Lions and randomly selected a draft class to try and compare to the actual Lion classes. Bois ran the process ten times and hoped to have a randomly selected team beat out Millen's 2006 extremely forgettable draft class.
He did. Six times. He randomly selected six draft classes out of ten that were more successful than Millen's.
He also had some Patriots-centric evaluations. There's no real question that the Patriots went through a dry spell in the middle of the decade, with Bill Belichick's "throw spaghetti at the wall and hope it sticks" technique failing to provide results on the field. In fact, the Patriots draft picks produced at a 15% lower rate than the average player at their draft position.
I'm sure if you re-ran this project for recent drafts you would see different results, but it's hard to argue with the scores from Bois' time frame.
Even more relevant is Bois' breakdown on the Patriots, titled, "3. The rules of NFL drafts apply to every team but the Patriots."
Here's an excerpt:
I took those figures above and plotted them against how much success each team found over the next five seasons. As one would expect, they're sprinkled diagonally: by and large, teams that drafted better won more games, and teams that drafted poorly lost more.
Bill Belichick's Patriots are the only team to exist outside of these rules. Their middle rounds were littered with guys who did nothing, or next to nothing, in the NFL. Their draft success ranked in the bottom third of the league during these seasons.
But even in 2009, those guys made up a large chunk of the roster. Nearly a third of the roster was made up of guys who were never drafted at all; the Patriots signed them for cheap and plugged them right in.
Go give his article a read. He does an awesome job.