A few things missing here:

1. Belichick recognizes that as much as he knows about football, the draft involves a lot of luck, and he’s going to miss as well. So what does he do? He trades down, amasses picks and more chances to hit on a winning number and never overestimates his ability in finding a blue chip player.
2. The ability to see the big picture when it comes league rules changes. He made his bones as a defensive coordinator but he moved his focus to the offense when the rules began to heavily favor their side of the ball.
3. Cap control. There is not enough ink spent on praising Belichick the GM and coach, they’re usually talked about separately but the fact that one man can do both jobs as well as he does them is truly astounding. Belichick says in an interview that defensive players often aren't good enough to play offense, so offense is harder to find. Look at the cap numbers on offense and defense here: http://overthecap.com/positional-spending/
   $63 million on offense. $33 million on defense. He practices what he preaches.