San Francisco ? Baseball’s new mandatory steroid testing plan appears to give cheating players every advantage they need to avoid detection while taking illegal performance-enhancing drugs, scientists and doping detectives say.

The plan to test all athletes beginning in March will fail, they say, because it ignores the many lessons Olympics officials learned while trying to curb steroid abuse.

“The plan of attack is a very bad plan and it sends a very poor message to fans,” said Dick Pound, head of the World Anti-Doping Agency.

The tests won’t be conducted during the offseason or postseason. With at least four months free from visits by doping detectives, cheaters have time to illegally bulk up and then rid their bodies of evidence before spring training.

And if all else fails, it takes five positive results before Major League Baseball will banish one of its players for up to a year.

Rob Manfred, baseball’s executive vice president for labor relations, didn’t return a call seeking comment. During a meeting of team owners last week, commissioner Bud Selig defended the program.

“Remember, before this agreement, we had no program. So we’ve made progress,” Selig said.

The mandatory testing plan is being imposed because between 5 percent and 7 percent of anonymous steroid tests among major leaguers came back positive last season. Those results triggered a provision in the sport’s labor contract requiring all players to be tested.

Typically, steroids are taken in combination and used in cycles of six to ten weeks. Experts say it’s likely users will time their usage around the testing and choose steroids that disappear from the body faster than ones widely used in gyms, such as nandrolone, which can be detected up to a year after use.

Powerful steroids such as methenolone enanthate, oxandrolone, and testosterone undeconoate that clear the body quickly are easily purchased online. There’s also Winstrol, called “winny” and made popular by disgraced Olympic sprinter Ben Johnson, which can be injected or ingested in tablet form. Winny tablets disappear within about three weeks.

Athletes are also turning to less dangerous applications, such as steroid-laced creams and gels that dissolve between the cheek and gum.

The only way to catch cheats who are using quick-to-clear steroids is to randomly test them the entire year, said Dr. Linn Goldberg of the Oregon Health and Science University in Portland.

“Unannounced and out-of-competition testing is the only way you can effectively do this,” said Goldberg, who is also a doping control officer for the U.S. Anti-Doping Agency.

Olympic athletes are tested for as many as 70 substances, including many “masking agents,” which may be legal but raise red flags when they appear in an otherwise healthy athlete. One popular masking agent is the diuretic Probenecid, which is legitimately used to treat gout. But diuretics, which increase urine production, can also help flush steroids from the system.

Baseball will test for a little more than two dozen steroids and related substances. Since they don’t have to worry about masking agents showing up in tests, experts say players may exploit a league requirement that any positive test be confirmed by a test on a second urine sample five to seven days later. In that time, a player could ingest a diuretic.

Also, with the average baseball salary surpassing $2 million annually, doping experts said cheaters can easily afford the kind of underground chemistry that is developing new steroids designed to evade detection.