The answer is, IMO, deterent. First positive is a one year suspension and the team will be permitted to void your contract if they wish. A repeat will result in a permanent ban from MLB, and this should a requirement for any nation participating in the WBC that any player banned from MLB for PED's would not be eligible to play professional ball in those countries.
Gio Gonzalez was found to be clean.
The rest, more info found on them of using.