There are certainly layers to all of these situations - and that's just it - each one is unique. Sure, we can see patterns, but correlation isn't causation.
I think the current level of public discomfort comes from a few factors, including cell phone video, increased media coverage, and general discontent. There's a a lot going on. People are upset. This particular thread has a lot of momentum right now.
and before anyone gets on my case - I'm not trying to explain away police brutality or racism - I'm agreeing with the OP that not EVERY person of color arrested/injured/killed by a police officer is a race issue.