Big league outfielder Marlon Byrd received a 50-game suspension after testing positive for Tamoxifen, a performance-enhancing substance under Major League Baseball’s joint drug prevention and treatment program. Released by the Red Sox on June 12, the 34-year-old Byrd is a free agent, but because he's under contract for $6.5 million this season MLB placed him on the restricted list, effective through Aug. 20, which results in a 50-day loss of pay.

The MLB Players' Association released a statement from Byrd in the wake of the announcement. “I made an inexcusable mistake," he's quoted as saying. "Several years ago, I had surgery for a condition that was private and unrelated to baseball. Last winter, I suffered a recurrence of that condition and I was provided with a medication that resulted in my positive test. Although that medication is on the banned list, I absolutely did not use it for performance-enhancement reasons."

MLB also announced a minor league suspension on Monday. Cardinals high Class A Palm Beach outfielder Mike Swinson tested positive for Methylhexanimine and will sit for 50 games without pay. The 22-year-old batted .184/.237/.230 with two triples in 87 at-bats during Florida State League play this season. St. Louis selected Swinson in the 12th round of the 2008 draft out of a high school in Douglas, Ga.