Veteran quarterback was considered the "driving force" behind the agreeing to a deal with receiver Antonio Brown, according to Jason La Canfora of CBS Sports.
La Canfora reported Brady "advocated strongly and consistently for the signing" despite objections from team officials.
"There is one reason he's there: Tom Brady," a source said.
Brady and Brown played one game together last season with the New England Patriots—connecting for one touchdown—before the receiver was released.
This article will be updated to provide more information on this story as it becomes available.