Bill Belichick the General Manager and Bill Belichick the Head Coach are pretty good friends. While some will always try to tear them apart, they're both really good at their jobs.
The analytics website numberFire broke down the offensive drafting ability of teams since 2000 and the New England Patriots topped the list. The method for evaluation consisted of comparing the draft capital invested in the position (ex: did the team use a 1st or a 3rd round pick on this player?) versus the production of the player. The production is grade on "Net Expected Points" (NEP), "which is a value assigned to each play based on how much it moves the probability of a team scoring on a drive from that point on the field."
The Patriots rank first in value added from the quarterback position, having spent the 28th most in draft capital in return for the 2nd most value since 2000. Taking Tom Brady in the 6th round helps. So does taking Matt Cassel in the 7th. Other teams at the top are the Seahawks, Packers, Saints, and Steelers, due to the consistency of their starters (Packers, Steelers) or due to the low draft capital invested (Seahawks spent a 3rd on Russell Wilson, the Saints didn't use a draft pick on Drew Brees).
New England also ranked 2nd in value at tight end, behind the Dallas Cowboys, but Bill Belichick has invested the 3rd most draft capital on the position since 2000. Essentially, for all of the draft picks that Belichick has used on tight ends, he's received roughly expected value.
The Patriots have had recent success at running back with Shane Vereen and Stevan Ridley, but Belichick has only invested the 19th most in draft capital, in return for the 18th best production. The fact that players like Corey Dillon and LeGarrette Blount hold down key snaps reduces the value of the draft picks, but shows how Belichick the GM uses alternative means to add value.
It's easy to say that Belichick struggles at drafting wide receivers, and the numbers show that those drafted by the Patriots aren't very successful. The drafted New England wide receivers ranked 28th in production. That said, the Patriots have invested the 28th most in draft capital, which means that the Patriots are getting what they're paying for: not much when compared to the rest of the league.
Belichick has knocked it out of the park when drafting quarterbacks, and according to the author Joseph Redemann, Brady "has produced more NEP than any other player in the past decade and a half." This study also does not include the offensive line, where Belichick has been extremely successful.
When drafting skill positions, Belichick is getting exactly what he's paying for; the poor production from the wide receivers might not be an indictment on his scouting, so much as a question about the allocation of his draft capital.