In answer to the question, maybe. The Farrell bashing IMO always was been over the the top. He won three division titles in five years, the only Sox manager to do that, and won a World Series. Benintendi, Bogaerts and Betts are all hitting better than last year. To say it's solely because of Cora ignores the fact that Bogaerts and Betts had very good years under Farrell in 2016 and ignores the fact that Bogaerts was hitting fine last year until he got hit in the Tampa game and ignore that Betts was having a decent year until the 30-game slump around August, which can happen to any player. Farrell didn't have J.D. Martinez, which is a huge upgrade over Hanley at DH, and although Devers hasn't quite hit like he did at the end of last year, he's still an upgrade at 3B over what the Sox had there the first four months last year. So the improved offense certainly would have made the record better than it was at this time last year. As for handling the pitching, Farrell was much better at it than he's given credit for by his critics. In fact, I would say it was his strength. So I don't know if the Sox would have 78 wins with Farrell, but I think they would definitely have more than they had at this point last year.
All this said, Cora was probably the right man for the job. In dealing with the young players on this roster and the make-up of the roster overall, I would say Cora is better suited for it. Farrell was probably better suited for a veteran roster like the team had in 2013.