So, what did they do wrong? You are pretty much treating this as though he was savagely beaten and maced for the kicks and giggles.
They used an excessive amount of force. There were ways in which he could have been brought down WITHOUT the use of a taser (there were THREE people after him, and a FOURTH in white seemed to quit the chase)
So, why is this wrong? Why do they need to do things the hard way?
It's already been established that there are risks associated with the use of tasers, and under certain conditions a taser can in fact be fatal. Tasers are great for apprehending someone who is committing violent acts of violently resisting, or if there are innocent people in the crowd. With a gun you could hurt or kill the offender or innocents, but with a taser there is significantly less risk. It is not risk free, but it is significantly lower.
As wolfpup has stated, tasers were intended to be used as a last resort before the use of guns, meaning when all other attempts to capture have failed.
It looks like these guys gave up as soon as they realized they were actually going to have to run after this kid and actually put their hands on him, so they just tased him and for all they knew it could have been fatal.
And before you (or someone else says) that if he died, well, it was his own fault. Well, again it goes back to the rights of lawbreakers. When you break a law do you automatically forfeit your life? Punishments are meted out by a court. Also, there need to be grounds upon which a law enforcement officer justifies their use of force. What was this justification? Did he verbally or physically threaten someone? Did he have a weapon? Did it seem like he was going directly for a target?
It looks to me like he was an idiot waving a towel around.
You should not be exposed to physical harm
beyond what is absolutely necessary during a police apprehension of you. A taser was not absolutely necessary. A little bit of physical fitness, intelligence, and, oh yeah, three grown men actually trying to make an effort on one 17 year old was absolutely necessary.
I don't know how much of the thread you've read, but I'll reiterate just in case:
I know it's a tough decision that law enforcement has to make between acting in a way that will protect people, but while not infringing on the rights of people. I would never want to make that decision, which is why I don't ever want to be a cop. It can be trouble if you act and trouble if you don't act. But as citizens we all trust cops to protect the rights of citizens. And I know from a cop's perspective a taser is great when compared to a gun- you have a reliable way of putting someone down without killing them, and keeping a potentially violent person (keyword: potentially) under control until you figure out what's what.
But it is easy, with such technology, to get complacent, and to start using it like duct tape: to fix every situation.
A little bit more physical exertion from perhaps more physically capable individuals might have changed the situation. But it looks like this kid could run circles around these guys for an hour, and it seemed like the use of a taser was because it was a "quick fix."
Anyway, essay time!