MLB.com released a list of their best-selling jerseys and Giants catcher Buster Posey is No. 1, followed by Yankees closer Mariano Rivera. Here's the top 20, which is based on online sales via MLB.com in 2013: 1. Buster Posey, San Francisco Giants 2. Mariano Rivera, New York Yankees 3. Yadier Molina, St. Louis Cardinals 4....