This may have been the case, but in this instance the deaths would've been more evenly spread amongst various members of staff. There was no real evidence either way which is why the defence didn't call anyone. Who would they have called? What you say may be true, but it doesn't overturn the fact she alone seems to have been the correlational factor.

How the babies died isn't really the legal dispute - the prosecution rests its case on WHEN the babies died. I'm prepared to believe this could've been chance on one or two occasions but 14 infants in 1 year - either Letby is a miraculous outlier in misfortune or she is a psychopath. The jury clearly believed the latter and I'm not sure debating the nature of how the babies might've died would overturn her conviction or add anything meaningful to her conviction.

Letby could be scapegoated for NHS failings and it would certainly be a good tactic by hospital bosses - but that doesn't make her conviction unsafe neither is Sir David Davis the sharpest politician in the drawer, nor is he known for his attention to detail.