If you have overlapping sets of poor vs black vs crime demographics and then compare things across an entire city that also includes very different demographics such as affluence etc... then it's not really surprising that you can come up with a "black people are stopped more" result.
Cops will be stopping more people in higher crime areas surely? They tend to focus on those (you'd hope?!) The fact that they frequently happen to correlate with low income + race is a social issue, not something the police can solve. They cannot solve skills and employment issues which are fed by education (and attitudes to education). It's not for lack of spending, some of these areas have the highest per-student spending in the country.
So how many black vs white people are stopped in each community within the city would likely give very different results. I think it was ferguson where people though having 70% black people stopped was "more" when the population of that community was over 85% (so actually under-represented). There's likely differences in the white people stopped in different areas - I expect way more in the poorer, higher crime ones than the affluent suburbs.
Who decides the areas that police focus on? The crimes committed and the politicians that the people elect so they can get elected again. Some have done a very bad job in Baltimore, have been divisive and tried to blame everything on the cops and hung them out to dry. Paying out multi $m settlements before anyone even filed paperwork or there was any investigation / court case to discover or decide fault.
I'm sure a lot of the population wants more police cover and more control of crime because they are the victims who suffer most from it. Other parts of the population seem to want no policing at all. Right now it looks like the police have stepped back as some people want and crime has exploded as a result.
Sad. But not a surprise. People forget that many of the police policies that they don't like are originally brought in because people demand it because they get sick of the crime. Who's voices should win? We have a democracy and people can vote for the governance that they want in their own areas.
There are of course other factors - the police are not the best in the world and do often seem amateurish, heavy handed and power-happy, a consequence no doubt of poor training and difficult recruiting good people due to low pay. But does anyone genuinely believe and want to claim that any amount of policing issues causes people to murder for instance? Let's not confuse symptoms with cause.