Roger Clemens didn't have to testify in front of Congress three years ago. But, his inflated sense of invincibility (fostered by decades of pampering by sycophants) made him do so. He now faces charges that he lied before that august body.
In the run-up to his trial for perjury, the conventional wisdom was that the judge would not allow the testimony of other athletes (most notably his old buddy Andy Pettitte). The judge thought the jury would be prejudiced by the inferences of juiced jocks. Without this damning testimony, it seemed that Clemens would again skate free.
Then his trusty lawyer decided to announce that the defense strategy was to go after Brian McNamee as a blackmailer. This effectively opened the door for previously excluded testimony. Nice going Roger, that's two strikes. Here comes the government's fastball, Clemenza.