Jason Giambi (1995-2001/2009) and Jeremy Giambi (2000-2002)
Older brother Jason Giambi made his Major League debut in 1995, hitting just .256 with 6 home runs in 54 games. He became the Athletics’ regular first baseman after Mark McGwire was dealt to the Cardinals in 1997 and took off as a team leader and producer. Jason hit .295 with 27 home runs in 1998 and .315 with 33 homers in 1999. His .300+ hitting continued in 2000 with a .333 average and 29 home runs. He was the 2001 MVP with a .342 batting average, and league-leading 47 home runs. After leaving for the Yankees as a free agent in 2002, Jason was back with the Athletics for the 2009 season but after hitting only .209, he was released in August.
For his career, Jason was a five time All-Star (twice with the Athletics) and finished a 20-year career with 440 homers.
Younger brother Jeremy was acquired by the Athletics via trade with the Royals, where he had served a backup role for parts of two seasons. On May 8, 2000, Jeremy and Jason became the eighth set of brothers to hit a home run in the same game.
In his three seasons with the A’s, Jeremy batted a respectable .272 in 270 games, serving mostly as a DH or left fielder. In 2002, the A’s parted with Giambi in a trade to the Phillies. Overall, Jeremy had a six-year MLB career with four different teams. Jeremy’s greatest legacy with the Athletics is probably the 2001 ALDS against the Yankees and not sliding at home in Game 3.
One Final Note: The brother of longtime third baseman Eric Chavez (1998-2010), Casey Chavez (2008-2014), served as the A’s bullpen catcher on its coaching staff.