That's a charge that should come as a surprise to no one. At the risk of massive oversimplification, where there's rage, there's roids. Here's Clemens in true form:
That's from the 2000 World Series—when Clemens and Grimsley were teammates on the Yankees. Mike Piazza of the Mets shattered his bat on a Clemens pitch, and the jagged barrel of the bat dribbled out to the front of the mound. Clemens proceeded to field the bat and throw it at Piazza, who was, as you can see, barely out of the batter's box.
Clemens later maintained that it was a mistake and that, in the heat of the moment, he thought the foot-and-a-half long piece of splintered wood was the ball. That explanation fails the bullshit, test, of course, if for no other reason than any kid who's older than 5 knows that you don't throw the ball at the runner to get an out, you throw it to the first baseman.
Considering that Clemens had viciously beaned Piazza in the head earlier the same year, more reasonable people (i.e., ones not hopped up on steroids) were led to believe that Clemens might have had something against the Mets' slugger.
We'll see how this plays out. I fear there are more asterisks in the baseball record book's future.