Hamilton was drafted out of
Edmonds High School in
Edmonds, Washington by the
Kansas City Athletics in the fifth round of the
1966 Major League Baseball draft. He spent six seasons in their farm system before receiving a call up to the Oakland Athletics in May of . He won his major league debut on May 29,
starting the second game of a
doubleheader with the
Texas Rangers. He ended the season at 6–6 with a 2.93
earned run average as the A's headed to the
1972 American League Championship Series against the
Detroit Tigers. Hamilton made only one appearance in the ALCS, blowing a
save opportunity in game four. He appeared twice in the World Series against the
Cincinnati Reds. He faced just one batter,
Joe Morgan in game five, and got a
double play on a fly ball to
Matty Alou in
right field in which
Pete Rose tried to score from third. In game six, the "
Big Red Machine" tagged Hamilton for four runs in just two-thirds of an inning. The A's returned to the World Series again in and , but Hamilton never made a post-season appearance either year. He was traded along with
Chet Lemon from the Athletics to the
Chicago White Sox for
Stan Bahnsen and
Skip Pitlock at the non-waiver trade deadline on June 15, . ==Chicago White Sox==