I don't see how Dez would make our offence that much better. Sure he is a premier WR but so is AJ Green or Julio Jones or Antonio Brown. All of them would diversify our offence........
...... but if you wanted to make the team better then you would contact the LA Rams and ask for Aaron Donald. He keeps a low profile, is regarded as a team player, regarded as one of the best at his position and seems to be the type of person that would totally fit into the Patriots system.
The fact that he can create an interior rush given his strength and speed is exactly what would make the Patriots more terrifying on Defence.