If a trade can be worked out, and it appears to have a decent chance of happening at this point, Farrell will become Boston's manager, as a contract for him there is a given. He is by far and away their top choice.
Farrell and the Blue Jays front office are said by sources to have had differences this year, when Toronto went 73-89, and he has only one year remaining on his Blue Jays deal. He's said publicly he's committed to Toronto, but it's reasonable to assume he'd prefer to have a multiyear deal with an organization that covets him.
Publicly, Blue Jays people have said they won't allow employees to make lateral moves, but most see that as a negotiating stance aimed at leveraging a better trade. One person familiar with Farrell's situation in Toronto said, "The people there would charter a plane to get him out."
Farrell served as Boston's pitching coach and worked closely with their front office.
The Red Sox interviewed four other men -- Tony Pena, Brad Ausmus, Tim Wallach and DeMarlo Hale -- but it's clear where their interest lies.