According to you, two things can't be the same at the same time.
1. Fred Kerley's arrest was a clear abuse of power and overstepping of bounds. The judge literally said so (that it should've been handled differently). If you watched the video, and didn't know who Fred was, it would be abundantly clear. Taking that to mean defunding the police, reforming, etc... that's a different story, but assuming he was aggressive and causing harm because of what he looked like and not what he did - that's about as much textbook racism as you can get.
2. Fred Kerley laying his hands on his wife was not as cut-and-dry (in the court of public opinion). The charges had been dropped/settled before but were revisited due to his arrest, which some took to mean the police validating their mistakes.
With allegations such as her punching him first and him retaliating, it's not really anyone's place to say. But it should also be clear: there is no one, in their right mind, supporting him for domestic violence. Difference is, that situation is murkier (and thus harder to comment on and raise as much attention to.
3. It would go without saying that unnecessary violence is unacceptable. Be it from the police, or from Kerley to his wife. The police 100% didn't know who he was when they were punching him on the ground, after he was tased, as he was unarmed. So to imply he is the "bad news": gives you a good indication of what you want to see, not what actually happened.
Maybe if people practiced a little more critical thinking, and a little less assuming, we wouldn't even have these discussions.