In the comments to my last post about World of Warcraft (WoW) being nerdy, people have hypothesized that sports are manly and non-nerdy because they are proxies for physical combat.
But most video and computer games popular among nerds are also proxies for physical combat. Most of the time spent in WoW is spent fighting virtual monsters, or fighting other players. At lower levels, WoW plays like a solo computer game in which other people are playing at the same time. But at the top level of WoW play, only teams of players are able to defeat the most powerful monsters, thus WoW is a team combat sport just like football, the primary difference being that it takes physical prowess to play football, but someone unathletic and/or fearful of getting physically hurt can enjoy WoW.
It's also interesting to note that football and WoW are both played most heavily by the same age group: teenagers. Although WoW skews older, because practically no one outside of professional NFL players plays football after they've graduated from college.