Vince, for a Terry stop, police need something less than probable cause.
Can be a combination of the totality of the circumstances: time of day, high crime area, furtive movements, etc.
You ALWAYS have to have probable cause under the 4th Amendment and these officers simply did not establish it in no way whatsoever. They did not witness him in the act of committing any crime whatsoever and did not identify any dangerous weapon. A Terry stop only allows a stop a frisk and that's if he appeared to have committed or about to commit a crime and its evident that it wasn't the case.
In addition, they approached him and yelled to him...Where's the money, where's the guns, where's the drugs before they even stated they were police officers and that would have been important to do if they were in plainclothes. I can fully understand this kid running from 3 people yelling at him about some money and drugs.
They simply should have waited and observed his actions prior to making an approach a little bit longer as there was no need to rush in and most importantly display their badges and state that they are police prior to saying anything else which would have prevented the situation to begin with. Ultimately they ended up violating his civil rights for no reason so the city will be liable of compensatory and punitive damages.
This kid is actually going to college to be a police officer so I guess his education is now paid for.