When you hear "Mariano Rivera" you also expect to hear "Enter Sandman." At this point, it's basically a Pavlovian response, like how hearing Charlie Blackmon's name immediately causes you to grow a full beard (That's what Pavlovian means, right?).
So, when Mo's son, Mariano Rivera III, made his debut on the road with the Class A Auburn Doubledays, the home team made sure he felt welcome, playing the Metallica song when he came out in the sixth inning.