was runner-up in 2001 after hitting .342 with 38 HR and 120 RBI. But that isn't enough to crack this all-time team.
No one else really comes close at 1B, but I did look at a couple of others briefly. Ferris Fain (1947-52) was the club's 1B from 1947-52, hitting .344 in 1951 and .327 1952 -- both good enough to pace the AL. He also had a very high OBP, as he walked a lot: 100+ walks five times, including 136 in 1949 and 133 in 1950. And Stuffy McInnis (1909-17) took over for Davis as the A's regular 1B in 1911 and held that job through 1917. He hit over .300 every year during that span, and stole 20 or more bases three times.
At 2B the starter is also quite clear. Although no 2B in Athletics history has played more than 1,200 games at the position, Eddie Collins (1906-14, 27-30) played the third most (996) and was by far the most productive. Collins started and ended his Hall of Fame career in Philadelphia, playing six full seasons and several other partial seasons for the club. In those six seasons from 1909-1914 he hit between .324 and .365, hit 10+ triples, and stole between 38 and 81 bases. And in four of those seasons he had an OBP over .440. He led the league in Runs from 1912-14, stolen bases with 81 in 1910, and was voted AL MVP in 1914. Eddie was a key member of four Athletics World Series teams (three of which they won).
After the Collins, there is a significant drop off in talent to consider. It is a close call, but Max Bishop (1924-33) is my choice as the backup. Bishop played most of his career for the Athletics, and was the regular at 2B during those years (though he never played more than 130 games in a season). Although Bishop had a mediocre average, his OBP was outstanding given his willingness to take a free pass. He walked 100+ times seven times, and almost always had an OBP over .400. His top HR season was 10 in 1930, and he didn't have much speed either, but he scored 100+ runs from 1928-31, and was an important part of the 1929- 31 AL champions.
Danny Murphy (1902-13) was an early member of the Athletics, playing in 1,412 games but splitting his time between 2B and OF. A significant contributor from 1902-1913, he hit for average and ran a bit as well. He had 15+ SB in eight seasons, and managed 17 triples in 1904 and 18 in 1910. One could make a case for him over Bishop, but I won't press it here.