Clearly all success is linear - so under Farrell Betts was destined to decline again. This is silly. Cora has certainly helped, but the kids were likely to do better.
Francona is the best manager the Red Sox have had since Dick Williams, and it's not close.
Cora was a phenomenal managerial prospect, and has shown that the promise was real. That said, I look back at 2013. Farrell looked terrific because of how bad the Red Sox were the year before, and he was an improvement on Valentine just by being a normal person who brought sanity to the workplace.
Last year was a negative vibe - despite a successful season - so that this year has been so good makes things seem particularly amazing. Cora has done a really good job - but there is a lot of future left. I mean Francona was excellent with analytics at a time when it was less prevalent. Farrell was shifting infielders on that stuff.
He has a lot of the positive of Francona, with the additional positive of speaking Spanish (which I think is damn near a prerequisite for the job now). But Francona was/is a flat exceptional communicator, and did a great job working with young players in a bananas market. Of course Francona had the best media training possible, managing in Philly and having to give media updates on Michael Jordan's progress.