Trading Devers and his $29 million a year contracts looks like an excellent move with him having a mediocre age 29 year with the Giants - currently posting a 786 OPS and 1.6 WAR. The real trade was to use the Devers money to pick up Wilson Contreras for $18 million a year (for 3 years) who is more productive at almost half the cost with a .912 OPS and 4.0 WAR. In addition the Red Sox got Kyle Harrison in the Devers trade - who (along with Shane Drohan) was traded for Caleb Durbin (.729 OPS and 3.3 WAR) , Andrew Monasterio (.776, 1.5) and Anthony Siegler (.708, .5).
Receiving anything back in return - was a bonus - the real win was unloading the big-money contract that will pay a declining skill hitter that we would have paid for 8 more years - until he is 37 in 2034. Of course Durbin on his own looks to be better than Devers right now and they pay him $800K and have 2 more years of team control.
So to recap: We got Contreras, Monasterio and Durbin who now cost us under $20 million a year combined - and the Red Sox gave up Devers and his $29 million a year contracts.
Devers contract made him replaceable by a highly paid free agent - he just wasnt worth it. Team control and good contracts are a necessity to build a winner. If you throw money in bad contracts away to keep a star on the decline the team will suffer.
Breslow gets an Aplus for this move now that we can look at other in hindsight.