After years of fighting any middleweight who was willing, while stockpiling impressive streaks of knockouts and title defenses in the process, unified champion Gennady Golovkin enters a dangerous challenge against Daniel Jacobs. The pair of hard-punching middleweights will headline Saturday’s HBO PPV card (9 p.m. ET) from Madison Square Garden in New York, where Golovkin, a native of Kazakhstan, has built a boisterous following thanks to four knockout victories inside “The World’s Most Famous A...