Given how often players who get big money contracts fail to live up to the level of their pay checks, its a wonder they are given out by the owners so often. As for the Pats, they have been very successful with a strategy of playing their middle of the roster better than most teams, and minimizing the people they are paying top 5 money to.
According to Miguel's page, the Pats currently have 21 players making over $2MM this year. That's over 40% of a 53 man roster. Football is a numbers game, and having a salary cap that his heavily weighted at the top (like, say the Jets usually have) is a prescription for failure (as the Jets usually have shown).
NO ONE has managed the cap better than the New England Patriots this century, NO ONE. They ARE loathe to hand out top 5 type contracts, but they are more than willing to pay their "middle class" very well. A great example of this, at a time when they will be facing a huge number (relatively) of hard contract choices with home grown talent, is the same time they have $62MM in cap space.