Count us as believers that baseball has finally started to take drug use seriously.

But it wasn’t the crackdown on steroid use announced last week that convinced us. It was the inclusion of amphetamines. Often called “greenies,” amphetamines, or other types of speed, may be used more often and widely than steroids.

Steroids were an easy target. If Major League Baseball and the players’ union had not endorsed tough rules and punishments for use, Congress was ready to act. Steroids will remain a blot on the integrity of baseball for years to come. As the new asterisk generation of ballplayers moves toward the Hall of Fame, its accomplishments will be viewed through the lens of performance-enhancing drugs. Superstar players, especially Barry Bonds of the San Francisco Giants, will be hounded by the taint of steroids for whatever remains of their careers and into history.

But amphetamines, that’s a different story. Even though the drugs are more common and have been used by players to help during the gruelingly long regular season for much longer, their use has never received the attention of other drugs.

The penalties for drug use adopted by MLB are serious. The first offense results in a 50-game suspension. The second earns 100 games. A third offense results in a lifetime ban. The NFL, NBA and NHL don’t come close to that with their drug policies, and the bar has been raised for them.

Performance-enhancing drugs, be they juice or greenies, undermine the game. They have no place in professional sports. MLB’s get-tough stance promises to clean up the national pastime.