The Athletics lost one of the best relievers in baseball, but acquiring the No. 3 overall prospect for a reliever is a home run.

Mason Miller made his debut with the San Diego Padres on Friday night, the day after being involved in arguably the biggest trade of the entire deadline. Miller isn't the closer for his new team, however, as was reported on Thursday. So on Friday, he came into the game in the top of the eighth with San Diego holding a 4-1 lead.

The San Diego Padres and Athletics agreed to a blockbuster deal on Thursday, hours before Major League Baseball's July 31 trade deadline passed (6 p.m. ET). The Padres will add All-Star right-hander Mason Miller and veteran lefty JP Sears to their pitching staff in exchange for a package fronted by shortstop prospect Leo De Vries.