Have you ever had to fire a good friend that did everything you ever asked them to do to the best of their ability? The NFL may be a harsh business, but that doesn't mean everybody involved has to be completely heartless.
Bosses should not become "good friends" with their employees if keeping the company in peak competitive condition is a priority. It clouds sound decision making in business. You may find yourself making a piss poor decision over and over again just to avoid an awkward and hurtful personal situation.