There is no need to bring Bill O'Brien back. Shawn Jefferson is the man for the job.
Jim Schwartz was brought into football by Bill Belichick in the early 90s in Cleveland. Adam Gase came into the league in Detroit under Schwartz. Gase also coached under Josh McDaniels in Denver. Shawn Jefferson became a coach in Detroit under Schwartz as well and was with Gase in Miami and NYJ. Jefferson is currently DAndre Hopkins position coach. We all saw the after game conversation between Hopkins and Belichick. AZ is reportedly looking to deal Hopkins and his massive contract. Hopkins is 32 with 2 years left on his current deal. He should be affordable to acquire. Maybe a 3rd rounder +. The Patriots have the cap room. Shawn Jefferson as the OC of the Pats would logically be able to get Gase to come in under him as the QB coach. Jefferson and whatever Wide Receivers Coach is on the staff could do wonders for Tyquan Thornton and other young receivers. Gase would be a good candidate to help Mac and Zappe progress. Jefferson and Gase would also have input with veteran Offensive Line and Tight Ends coaches.