It is one of the many conundrums faced by the modern ballplayer: what song to play when you're walking up to the plate or on to the mound. On one hand, it's a personal and private choice. You want something that's going to pump you up and get you in the right frame of mind. On the other, it's like letting a stadium full of people peek at your playlist — and judge you accordingly. The situation is unique to baseball. No other sport affords every player such an individualized spotlight and personalized control of the stadium stereo. The only parallel is a WWE wrestler's entrance music.