I remember the OJ trial came up when I was with some NYC Legal Aid lawyers, who were probably all in the liberal-batshit insane camp and they all thought OJ was guilty but the prosecution failed to prove its case and did really shoddy lawyering, especially with respect to their witnesses and chain of custody. OJ also had the legal equivalent of the Dream Team-Cochran, Kardashian, Shapiro, Dershowitz and F Lee Bailey; it bankrupted him but he walked.
The prosecution has to prove beyond a preponderance of the evidence, which is a pretty high standard; all the defense has to do is poke enough holes in the prosecution's case so it can't meet it while convincing the jury that Chauvin isn't the person responsible for Floyd's death under the statues he's been charged with. Most people don't understand criminal law, even most lawyers don't unless that's what they specialize in. Nelson seems knowledgeable and experienced, going by how many times the judge has overruled the prosecution. He hasn't presented his defense so it's still up in the air, as far I'm concerned.