Victor Conte, the founder of BALCO who spent time in prison for distributing steroids, is certain that Melky Cabrera is far from alone in using performance-enhancing drugs.
"I'm not going to name names," Conte said in an interview with USA Today, "but I've talked to a lot of top players in Major League Baseball, and they tell me this is what they're doing. There is rampant use of synthetic testosterone in Major League Baseball."
Cabrera, the San Francisco Giants outfielder, was suspended 50 games Wednesday after testing positive for testosterone. Cabrera's suspension is the first of a high-profile player since Ryan Braun, last season's National League MVP, had his suspension overturned by an arbitrator last winter.
Conte was asked by USA Today to make an educated guess as to how many players in baseball are using PEDs.
"I would say," Conte said, according to the newspaper, "maybe as much as half of baseball."
Major League Baseball isn't putting much stock in Conte's estimate.
"There is no way that Victor Conte would have information that would allow him to have any basis on that," MLB vice president Rob Manfred said, according to USA Today. "He's just making that up. It's a guess.
"We use the very best, most sophisticated methodologies that are available."
Drug-testing labs check urine for its ratio of testosterone to epitestosterone, which usually is 1 to 1 in adult males. If the lab notices any abnormality, it conducts an isotope ratio mass spectrometry (IRMS) test to determine whether the testosterone came from outside the body.
Conte, whose Bay Area Laboratory Co-Operative was at the center of a steroid scandal that enveloped several top-level athletes, including Marion Jones and Barry Bonds, says testing procedures still can be beaten, though.
"To circumvent the test is like taking candy from a baby," he said, according to USA Today. "It's so easy to circumvent. I call it the 'duck-and-dodge' system. The only people that get caught are the dumb, and the dumber."
Testosterone helps build muscle mass quickly and aids in recovery time for athletes, but its use carries health risks like liver, heart and circulatory damage.
Some in baseball believe the solution to performance-enhancing drugs in baseball is instituting stronger penalties.
"I can say that certainly the majority of people who are in this game care about the integrity of the game," Diamondbacks manager Kirk Gibson said, according to the Arizona Republic. "We're all committed to cleaning it up. Obviously, there's not a big enough deterrent if it continues."
For Gibson, whose D-backs trail the Giants in the NL West, 50 games doesn't cut it.
"I don't have an exact number," Gibson said, according to the Republic. "I think it should be a minimum of a year (for a first positive) and after that it should just be banned."
Information from ESPN.com's Jayson Stark, ESPNNewYork.com's Mike Mazzeo and The Associated Press was used in this report.