Well, he alleged that Pujols was on 'roids, and that didn't go over too well.
Pujols threatened a lawsuit. And now the dude's fired.
At LAT, "Jack Clark loses radio show after Albert Pujols PED allegation."
The St. Louis Post-Dispatch has the background, "Clark accuses Pujols of steroid use."
And there's video at ESPN, "Albert Pujols: I'll sue Jack Clark."