You've posted this in appeals, so it appears this is in the Court of Appeals, not the trial court stage.
The trial judge can find the defendant not guilty at the close of the prosecution or defense cases, if there isn't enough evidence to sustain a guilty verdict. (Penal Code 1118.1.)
As long as there was evidence that could have supported the jury's verdict, the Court of Appeal will not overturn the verdict.
The Court of Appeals didn't see the witnesses testify, so the justices will not try to second-guess the jury to decide whether they were credible. The jury could have decided they believed the witnesses despite the change in their stories.
Second degree murder does not require the specific intent to kill. The "malice" required is not anger or a wish to do someone harm; it is doing something so dangerous that it presents a substantial likelihood that another person will be killed, without regard for the lives of others. That's why repeat drunk drivers are sometimes charged with murder when they cause a fatal accident.
The answer to your question is yes, but it happens very rarely. When it happened in Boston in the 90's it made international headlines. Nineteen-year-old British nanny Louise Woodward received a mandatory life sentence when the jury found her guilty of second degree murder in the shaking death of an eight-month-old baby. However, the Boston judge rejected the jury's finding, reducing the ultimate result to a guilty only on involuntary manslaughter, freeing her to go home to England.
The media sensationalism of the case aside, this was a rare event in the legal world.
California atty Robert Marshall has given you a thorough analysis of how this plays out under your state's law.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Although one answer was geared toward the appeals process, should this case still be pending sentencing, the defendant's attorney can file several motions prior to the sentencing.
Motions to set aside the verdict, motions for a new trial, etc. are all things that should be explored. Appeals are no longer about the facts, they're about procedural and legal errors.