On a recent weekend, Bob Costas was broadcasting the Cardinals game in St. Louis, Dick Enberg was behind the mic at the Padres game in San Diego, and Vin Scully was calling the Dodgers game in L.A. It was an epic triple play-by-play.That these three greats are still at it, and in fine form, says a lot about them, but also about baseball ---- a sport which, due to pace, setting and style lends itself to poetry.At 64, Costas is the baby of the group. Enberg is 81; Scully 88. They all began broadcasting sports in their early 20s, meaning each has legacy knowledge about baseball that Wikipedia and YouTube simply can’t replicate.Come September, you’ll be hearing and reading a lot about Enberg and Scully, both of whom plan to retire at season’s end.