We have the 4th-most cap space (more than $50m more than Miami and Buffalo), very little dead money and haven't stolen from out years like many teams have with voidable contracts. Plus an unusually good haul to come in this draft - number 14 is their highest pick in a decade, and they are projected to have 11 picks altogether (including compensatory picks in the 4th, 5th and 7th rounds). So with 6 picks in the first four rounds they plenty of ammunition to move up if needed.
Belichick noted we've had the among the lowest total payouts over the last three years.
So now the Pats are actually finally in a good position roster-wise - we sold out some in the last years of Brady when we traded for some players at the expense of draft picks which hurts in terms of salary. And the bad picks (Harry etc,) are now mostly off the team and behind us.
NFL salary cap space estimates for all 32 teams
overthecap.com