Bear with me on this one. Not the Betts/Syndegaard trade, but this:
Mets receive Mookie Betts and CJ Chatham
Red Sox receive Jeff McNeil and Jed Lowrie
Before you blow up, here's the logic: McNeil was the Swiss army knife of that team and could easily plug either into our LF (if Lowrie is vaguely healed) or 2B. He's a high average/OBP left handed bat who can get on in front of JD and Xander and Devers.
Lowrie is only on contract through 2020 @ $10MM, which is a tough pill for a team trying to shed payroll, BUT McNeil is under team control for the next 5 years. This sets us up to win now and win in the future.
(Also: https://www.baseballtradevalues.com/trade-simulator/ thinks the deal is fair!)