I would assume it is just whether the ref wants to call it a flagrant or intentional foul. Before hockey ended checks to the head with shoulder contact or hits from behind, they would give guys extra minutes at their discretion to call it, if at all, two minutes, four minutes, or a five-minute major based on what they thought the intent was. I heard a lot of adult words from the coaches going after the refs growing up in travel hockey based on what they didn't call a two-minute, four-minute, or five-minute major when it was all a gray area at the refs discretion. I don't think it is a good idea in any sport to allow the refs to determine what level of a foul or penalty it is at their discretion, because the rule books should clearly state what the different levels of penalties are for such flagrant or intentional behavior in this case. If a player agressively throws their shoulder into a guy to get the basketball, it could be labeled a flagrant or intentional foul up to the ref.