If you read the story, I think you would realize that the gentleman was likely going to receive a 'citation" for allegedly selling drugs.  He chose to attempt to leave the area rather than receive the citation....another individual was, I believe, cited and released.

There are no "easy" answers for the police in such situations.  They either enforce the law or they don't...The officers chose to enforce the law and to do so with a minimum of force.  Mr. Walton gave them two choices:  let him walk away and, thereby, not enforce the law or take him into custody.  They chose the latter and Mr. Walton chose to resist arrest.  The escalating level of force was predictable at this stage.   

The crowd, of course, helped escalate the violence by taunting the officers and encouraging Mr. Walton to resist.  In this instance I feel the police acted with restraint and the force they applied was consistent with the continuum of use of force expected of officers.  Gary Crum