The popularity of sports documentaries is not recognized enough. Maybe it’s because a lot of the favorites find their audience on TV, particularly as part of ESPN’s “30 for 30” series. Perhaps they aren’t considered “important” enough by the documentary community, even when they deal with serious issues as in the case of Steve James’s most recent and most overlooked film, Head Games. Like music docs, they may be disregarded as insignificant fare mainly targeted to a particular fanbase. But with many sports, that’s a very large fanbase we’re talking about. Professional ice hockey is the least followed of the four major team sports in America, but millions of people do watch it, and the number has been on the rise these past few years. So, there’s definitely a large demographic who’ll be interested in Alex Gibney’s The Last Gladiators, a documentary about NHL enforcers with a predominant focus on former Montreal Canadiens “goon” Chris “Knuckles” Nilan. This is a demo that likely won’t know or even think about the fact that this film was made by a tremendously prolific and highly acclaimed director. Many of them would sooner see this than Gibney’s other new docs, which tackle sexually abusive priests and the story of Wikileaks, and they very well might have seen his baseball doc, Catching Hell, but not his Oscar-winning doc, Taxi to the Dark Side.