Update (6:12pm): Via Marc Carig, Brian Cashman responded to the accusation by saying it was simply “not true.”
Original Post (5:30pm): Via Peter Gammons, the Yankees and other teams tried to convince lefty Andrew Miller to use his June 15th opt-out clause presumably so they could sign him, which would be considered tampering. The Red Sox agreed to call Miller up and put him in the rotation, so the opt-out never came into play anyway. Still, accusing teams of tampering is a pretty serious accusation even though it probably happens all the time. I’m sure a bunch of Gammons-Red Sox cracks will follow, but this is something MLB will probably look into.