The Patriots got busy on Monday afternoon as the NFL’s free agency negotiating period opened with a frenzy. New England made four significant signings in the first hours of the window, including some major splashes on defense and a much-needed upgrade to the offensive line.

The NFL legal tampering period opened on Monday at noon, and the New England Patriots wasted little time making moves. The biggest among them in more ways than one was the fourth they made: signing defensive tackle Milton Williams,