Former Astros pitcher Andy Pettite was supposed to be the smoking-gun witness in the second federal perjury trial of Roger Clemens. Instead, he may well be the reason that the government’s case is firing blanks. 

As he did in front of Congress in 2008, Pettitte testified to federal prosecutor Steve Durham on Tuesday that Clemens told him he used human growth hormone in 1999 or 2000, but that when Pettitte–who admitted to using HGH himself in 2002 and 2004–brought the subject up again in 2005, Clemens said that it was only his wife, Debbie, who had used HGH, and Pettitte’s recollection was mistaken. (Clemens infamously used the word “misremembered” in his own Congressional testimony.) 

But it was under cross-examination Wednesday by defense attorneys that Pettitte’s testimony started to look bad for the prosecution.

By the time it was over, ESPN.com’s Lester Munson noted, federal district Judge Reggie Walton “was seriously considering an argument from the Clemens legal team that could force the jury to eliminate any consideration of Andy Pettitte’s testimony that Clemens admitted to him that he had used HGH.”

As the Houston Chronicle‘s Stewart M. Powell and Regina Garcia Cano reported, the key moment was this:

“As you sit here today, you believe in your own heart and your own mind that you very well might have misunderstood Mr. Clemens in 1999 or 2000?” Clemens’ defense attorney Mike Attanasio asked Pettitte. “You think it was 50-50 that you might have heard it, might have misunderstood it? Is that fair?”

“I’d say that’s fair,” Pettitte replied.

Garcia Cano called the testimony “a wild pitch … instead of confirming his previous story, Pettitte single-handedly may very well have created ‘reasonable doubt’ in the minds of the jurors with his ’50-50′ admission.”

Sportswriters on Twitter seized on Pettitte’s seeming about-face. 

Yahoo! Sports’ Dan Wetzel went with a Godfather 2 joke (as did Deadspin hours later):

And Houston-based MLB.com columnist Richard Justice unfurled one of his patented multi-tweet comic riffs:

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At NBC Sports’ Hardball Talk, Craig Calcaterra argued that Pettitte’s testimony, while “pretty bad for the prosecution,” was also nothing new—and that to say that Pettitte flip-flopped, as Wetzel, Justice, and CBS Sports baseball writer Jon Heyman all did, is entirely inaccurate:

Andy Pettitte didn’t change his story. Not one bit.

Pettitte was deposed by the government in 2008.  You can read his entire testimony here.  The relevant parts of it come on pages 25-28.  There Pettitte recounts the two conversations he had about PEDs with Roger Clemens: one in 1999, one in 2005. As he did in court today, he said then that he initially believed Clemens told him in 1999 that he used PEDs. Then in 2005, Clemens said something else: that it was his wife, not Clemens himself, who used.

Obviously, it’s possible that Clemens was lying in 2005. The heat was on PED users by then. He may have wanted to make people think that he never used PEDs at all.  That may have been why Clemens said what he said about his wife, and it would not be at all unreasonable for Pettitte to assume in 2005 that Clemens was lying.

But Pettitte didn’t assume that. At least not publicly

Perhaps the most notable thing Pettite said in front of Congress back then was, “I’m saying that I was under the impression that he told me that he had taken it. And then when Roger told me that he didn’t take it, and I misunderstood him, I took it for that, that I misunderstood him.”

Calcaterra continued:

In light of that previous testimony — that Pettitte, in his own mind, concluded that he misunderstood Roger Clemens in 1999 — there had to be zero expectation that he would say with any degree of certainty this morning that Clemens told him he used PEDs in 1999.  For him to do so would require him to contradict his previously-sworn testimony.

And he did not contradict his previous testimony. It was totally consistent.

In other words, not only is it incorrect to say that Pettitte changed his story, but to do so is to accuse him of committing the same crime Clemens has been charged with, either then or now.

That being the case, the prosecution should have seen this coming, Calcaterra wrote. Instead, even the presiding Judge Walton called them out for failing to undo the damage when they got a second crack at Pettitte after Attanasio’s cross-examination, as the New York Times‘ Juliet Macur reported:

“His testimony now before the jury is, ‘I don’t know,’ ” Walton said to Durham. “I thought that what we would hear is, ‘Mr. Pettitte, currently, what is your memory of what Mr. Clemens told you back in 1999?’ ”

“I was waiting for you to ask, and you didn’t ask that,” he told Durham.

ESPN’s Munson, a lawyer, explained that the big question now is whether Walton might rule that Pettitte’s “50-50” statement falls short of the “preponderance” of evidence standard that is often expressed as 51 percent: 

Durham and his team will argue that the quality of the evidence is the important criterion and that quantitative analysis has no role in deciding what evidence a jury should consider. They may also argue that the “50-50” phrase is an idiomatic expression of colloquial American English and has no connection to the 51 percent standard of the rules of evidence.

It will be a difficult argument, but it is an argument the prosecution must win to preserve its chances of obtaining a conviction of Clemens.

Pettitte and former Yankees trainer Brian McNamee were expected to be the only witnesses to testify that Clemens used performance-enhancing drugs, with Pettitte, as a friend of Clemens’, a born-again Christian and someone who has owned up to his own transgressions, was considered the more credible witness of the two men.

The drama will continue today with testimony from FDA investigator and former IRS agent Jeff Novitzky, who was also involved in the Barry Bonds/BALCO prosecution and the since-ended investigation of Lance Armstrong. Novitzky began testifying Wednesday.