Ok being serious here for a sec.

Boxing have always proven its worth in real fights. There are many Martial Arts that are shit in real fights, MMA has proven that. Muay Thai and Boxing are the truth when it comes to real fights. Many of these other striking arts are more like dances than worthful fighting styles.

Bruce Lee is the only actor who is willing to actually fight anybody for real to prove his true fighting skill. It may not be super martial arts when he actually does fight but IMO he would be a tough fight for anybody. It may not be like the movies but Bruce was always fit and fast but who knows how well he can take a punch or brake off a clinch and submissions. As much as people would like to tell all these stories about Bruce Lee....there is still a lot of myth behind him.

If Bruce Lee vs Manny Pacquiao would happen, it could be as quick as a single punch from Pacquiao.