They've done this to try to relax the protests. It is risker to try to prove that this is second degree murder, instead of trying to prove 3rd degree. If they can prove it and convince a jury though, they're going to bring the justice that is required -- plus the fact that they'll springboard their careers (anyone prosecuting this case, etc) -- which is really what most of these people care about.
Very risky to go for 2nd degree, as you could get an acquittal which will kill your career and incite further protests. Yet again, they're mostly trying to relax the protests with this sort of thing. It's what MANY were calling for. We'll see if it plays out.
Switching the murder charges to 3rd degree to 2nd degree is no doubt to appease the public but I'm a bit taken back by charging officers involved. One of the guys involved, Thomas Lane, was a rookie that had graduated less than a week from the academy and took orders from Chauvin to keep Floyd on his stomach with knee pressure on his back to subdue him. If Chauvin's a 19 year vet and you're a rookie, you're going to take orders from a more tenured officer. As for the other two, not sure why they should be held liable for their coworkers negligence. They did not know Floyd and the neck position that Chauvin had Floyd under is legal under Minneapolis Police Department's guidelines and policies.
They arrested the other 3 officers because of public pressure which is setting an extremely bad precedent for officers to be held liable for something their partner might fuck up on. The charges on the other officers will not stick and the Minnesota AG knows this well which is why it's concerning that these three are in jail right now. Chauvin's responsible, hold him accountable and take him to a trial with all the facts laid out and make a determination.
I actually saw the portion about Lane, and I don't think his charges are going to stick. He's most likely going to have to be rehired by Minneapolis PD tbh -- union is going to fight hard for him, and they're going to say that there was no cause to fire him. Only issue in this line of thinking is that he may be in a probationary period, and may be able to be fired without any sort of union protection. We'll see on him.
The others -- well I mean, guess they're going to charge them b/c they didn't actively try to stop it or at least verbally try to stop it. No one is going to tell them that they have to fight a coworker, but Lane's response should be good enough (IMO)
Neck position that he was put into is LEGAL for certain circumstances, though the circumstances that Floyd was put into was not that.
This is going to be the case that legal experts, police departments, police unions, police reform groups, and so on are going to be watching this case INTENSLY. This could set a precedent that changes the police forever.