We do not know it to be a fact that Johnny is an alcoholic, though it is pretty clear that he likely is one. His high school coach who went and lived with Johnny this summer and loves the kid...he knows it to be a fact.
He very well MIGHT be. Can't really dispute that, but people throw the word "alcoholic" around rather irresponsibly.
There is an enormous difference between someone who drinks too much or drinks irresponsibly and/or parties too much and an actual alcoholic.
For the people who are absolutely convinced that he is an alcoholic, I wonder how many legitimate alcoholics you actually know.