"Anti-doping experts and political figures have taken great pains in the last two weeks to laud Major League Baseball for a new agreement to test players for human growth hormone beginning next spring. When that happens, MLB could beat the NFL to the distinction of becoming the first U.S. pro sports major league to implement HGH analysis, after years of entrenched resistance to blood testing.

But baseball's program contains a loophole that could allow use of HGH from opening day until the end of the World Series, experts say, at a time when a rigorous testing program could make a big impact.

For the first year at least, MLB will conduct more than 1,000 HGH tests — more than any Olympic sports body ran last year — but only in spring training and then again in the offseason. There will be no testing during the 162-game regular season and playoffs, unless league officials can establish "reasonable cause" to target a player, such as obtaining evidence he placed an order for the substance."