Victorino's original injury -- the one that has put him on the disabled list twice this season -- was a right hamstring strain.
But discomfort in his back might be related.
Third baseman Will Middlebrooks is also having a slower-than-expected recovery from a fractured right index finger.
Middlebrooks has also been shut down from baseball activities due to increased swelling.
In part because of Victorino's prolonged absence, the Red Sox are getting No. 5 prospect Mookie Betts some exposure in right field at Triple-A Pawtucket.
"There's been some correlation to that," said Farrell. "Tonight will be the second time he's been in right field. We're just trying to get him exposure to both center and right field in the event that some further discussion and ultimate decision is made to bring him here. That has not happened yet."
Middlebrooks and Victorino had both been playing in Minor League rehab games for Triple-A Pawtucket earlier this week.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.