I would agree that many do their job well. Another chunk do their job well enough but are very condescending and patronizing to people which usually does the opposite of deescalation, and another chunk are just out looking for action. Pull people over for some BS just to see if they can find something bigger...etc.
Most are subject to the same mob mentality as some moronic protesters. Cops are just people. They follow the crowd, get caught up in the moment, as these officers did. Many of us may have done the same unless someone told us to stay back. You can say you wouldn't have but you don't know until you are in it. Your blood is pumping, you feel like youre in an action movie, the bad guys are shooting at you. Most people literally do not have the ability to control that adrenaline. If you were to ask some of these cops, they would probably just say the don't remember much, their "training" just took over or some

, which is another way of saying, "my fight or flight kicked in and I had no control over my own adrenaline".
If you told any of those cops that day that they would be responsible for shooting an unarmed UPS driver and another bystander, I guarantee you they would have called in that day. Nobody wants to murder someone. That said, leadership definitely needs to be held responsible for the outcome.