Dick Green (1963-74) played 1,158 games at 2B for the Kansas City and Oakland Athletics, spending his entire career with this franchise. A low average hitter, his best offensive season was in 1969 when he hit .275 with 12 HR and 64 RBI. He also didn't hit very well in seven post- season series (batting only 13-84 for a .155 average in those contests), so he doesn't really come close to making this all-time roster.
Although not a serious candidate for this all-time team, I will mention that Nap LaJoie was the 2B for the Athletics first season. In 1901 he had one of the finest all-around offensive seasons of all-time, as he took the AL Triple Crown by hitting .426 with 14 HR and 125 RBI. He also had 48 doubles, 14 triples, 232 hits, 27 SB, and 145 runs. After many fine years in Cleveland, he returned to the Athletics for his final two seasons in 1915-16, but in his forties, he was just a shadow of his former self.
Sal Bando (1966-76) has played in the most games at 3B for the Athletics (1,446). After two partial seasons in Kansas City, he moved with the club to Oakland in 1968 and soon became a key slugger during their pennant-winning streak in the 1970s. His best numbers came in 1969 when he hit .281 with 31 HR, 113 RBI, and 106 runs. In 1971 he was the runner-up AL MVP based on a .271 average, 24 HR, and 94 RBI (teammate and rookie phenom Vida Blue took the honors). Then in 1973 he came in 4th in MVP voting, and in 1974 3rd in the tally. Although in 1976 he hit 27 HR and 84 RBI, and even managed a career-high 20 SB, he was granted free agency after the season and went to the Brewers to play out his career.
The backup spot is a tough choice, but I’ll go with Frank “Home Run” Baker (1908-14). After a brief 1908 campaign, he played full-time for the Athletics from 1909-1914. Although only six seasons, he was amongst the league leaders in most offensive categories in most of those seasons and garnered some MVP consideration in four of them. He earned his nickname on the basis of leading the league in HR four times during this dead-ball era, with totals of 11, 10, 12, and 9 from 1911-14. He also paced the league in RBI in 1912 with 130 and in 1913 with 117. Not a one-dimensional player, he hit for high average (.321 for the Athletics), hit plenty of doubles and triples, and stole bases as well, with 30+ in three seasons.
I consider this a close call, as one could make a case for Eric Chavez (1998-2010). A consistent run-producer, Chavez hit 20-34 HR in his seven full seasons with the club. He also smashed 100+ RBI four