Every person deserves a defence regardless of a lawyer's personal opinion.
That right there is why I could never be a lawyer.
As for this particular case - disgusting attitude that the coach had. His fingering the crowd after just proves what a "gem" he is. Question: If the kid hadn't hurt his wrist, is it still considered assault? It reminds me a lot about hockey (oooh, note the tie-in!) when it seems that the outcome more determines the severity of the punishment. I've seen some bad hits that thankfully didn't result in more major injuries go unpunished. Why is it that the consequence of injury severity weigh on the outcome (I mean, a kid tripped doesn't always end in a broken wrist!)
It is up to the Crown to prove all elements of the crime charged for as the Charter notes it is legal guilt that is at issue. "Any person charged with an offence has the right..to be presumed innocent until proven guilty according to law in a fair and public hearing by an independent and impartial tribunal."
And it is a duty upon lawyers to provide the best defence possible for all accused as allowed by law.
Per the BC Code of Professional Conduct - Canons of Legal Ethics:
It is a lawyer’s right to undertake the defence of a person accused of crime, regardless of the lawyer’s own personal opinion as to the guilt of the accused. Having undertaken such defence, the lawyer is bound to present, by all fair and honourable means and in a manner consistent with the client’s instructions, every defence that the law of the land permits, to the end that no person will be convicted except by due process of law.http://www.lawsociety.bc.ca/page.cfm?cid=2637&t=Chapter-2-%E2%80%93-Standards-of-the-Legal-Profession#2.1-3