A PED suspension typically is handed down after a failed drug test, not on the basis of rumors. A player could contest the validity of the drug test, or whether he knowingly consumed a banned substance, but the drug test represents more than a rumor.
Unlike a domestic violence suspension, the PED suspension is rarely accompanied by a criminal investigation and possible prosecution. The PED suspension may be the only consequence the player suffers (other than loss of endorsements, etc.).
I suspect the Red Sox are off the hook for Wright's roughly $100,000 prorated salary for the 15-game suspension. Perhaps the Sox should donate that $100,000 to a program that provides services to victims of domestic violence.