
Quoting
Taxing Matters
When it comes to public figures the U.S. Supreme Court has held in a series of cases that in order for the public figure to successfully sue for defamation the public figure not only needs to prove that the statements made were false statements of fact that injured his/her reputation (which is necessary for any defamation claim) but in addition must prove that the person made the statements with actual malice or reckless disregard for the truth. Because of that, it is much harder for a public figure to successfully sue for defamation than it is for some regular person who is not in the public eye.
That said, you do run a potential risk of being sued if you go around stating as fact that the coach committed sexual harassment. Even if the coach were to lose the lawsuit, it could cost you many thousands of dollars to defend the claim. Also, I would hope you would not want to run the risk of adding to trashing the reputation of someone else merely on unproven allegations or rumors.