Well, it's sort of complicated to answer this question. The crux of the matter is that the defence teams simply didn't appear to realise the significance of ToD at the time of the first trial. In my opinion, they made two separate (but connected) mistakes: 1) they didn't seem to realise that there was ample evidence/testimony available to make a very persuasive argument for a ToD definitely before 10pm, and almost certainly before 9.30pm; and 2) they didn't therefore realise that existing computer log evidence on Sollecito's laptop would allow them to make a persuasive argument that at least one of Sollecito and Knox (and probably both of them) must have been at Sollecito's apartment at the time of the murder.
I know I've said it many times before, and I know that some pro-acquittal commentators here disagree with it, but I think the defence teams did a poor job in the first trial. I think they slipped up in many areas, of which this was perhaps one of the most crucial. Yes, I also agree that the odds were stacked against Knox and Sollecito in the first trial, owing to the mendacity and cunning of the prosecutors, the credulous and illogical nature of Massei's court, and the prevailing public opinion at the time. But even notwithstanding all that, I truly believe that a better defence performance might well have resulted in Knox's/Sollecito's acquittals in the first trial.
It's also true to say that the defence were stymied on the ToD issue somewhat, when Mignini moved the prosecution ToD back by over an hour in his closing argument. I think it was improper judicially for Massei to have allowed this change, since it gave the defence teams scant opportunity for rebuttal. But even before this Mignini stunt, i think that the defence teams should have realised - long before the Massei trial started in fact - that they had a very strong ToD-and-computer-evidence-related argument for their clients' non-involvement in the murder. They should in my opinion have employed this argument strongly in Massei's court. That they didn't do so was, in my view, a significant failing on behalf of the two defence teams - especially Sollecito's.
I think that the introduction to the Knox/Sollecito teams of US-based specialist defence consultants, who are able to devote sufficient time, expertise and experience to putting together the best possible defence strategy, has had a very significant effect on the quality of Knox's/Sollecito's defence. You won't see or hear these consultants in public: it's a good strategy to keep them behind the scenes, plus they are not qualified to practice courtroom law in Italy. but I believe they've made a very large difference. And I think that Knox and Sollecito will owe their forthcoming acquittals in large part to the work of these consultants. I only hope that their fees won't have long-term adverse financial impact upon the families.