Bob Welch was a very consistent pitcher with the Oakland A's. No pitcher in the past two decades had as many wins in a season as Welch did in 1990, when he recording 27 wins in the season.
He went on to win the CY Young Award in 1990 and made his only All-Star appearance in an A's uniform. That season, he was 27-6 with a 2.95 ERA in 35 games starts, with two complete games. He struck out 127 batters while walking 77.
For his career with the A's from 1988-1994, Welch went 96-60 with a 3.94 ERA. He had 14 complete games, five shutouts, and 677 strikeouts vs. 469 walks.
Mark Mulder pitched for the A's from 2000-2004. In that span, he went 81-42 with a 3.92 ERA, with 22 complete games, eight shutouts, and 668 strikeouts.
Rube Walberg pitched 11 years for the A's from 1923-1933, compling a record of 134-114 with a 4.11 ERA. He pitched 125 complete games, with 15 shutouts.
Barry Zito went 102-63 with the A's from 2000-2006. He had a 3.55 ERA and pitched 9 complete games and four shutouts, striking out 1,096 batters while walking 560.