it. Guetterman graduated from Oceanside High School in Oceanside, California, and went to Liberty University, where he was coached on the baseball team by former major league pitcher Al Worthington. During his time at Liberty, Guetterman set school records that still stood in 2010 for starts (47), innings pitched (), wins (29), complete games (30), and shutouts (seven). As a hitter, he batted .325 with 82 runs scored, 11 home runs, and 108 runs batted in (RBI). In his senior year of 1981, he was selected as a 1st Team All-American in the National Association of Intercollegiate Athletics. That same year, the Seattle Mariners selected him in the fourth round of the Major League Baseball (MLB) Draft. First professional seasons (1981–85) In 1981, Guetterman began his professional career with the Single-A short season Bellingham Mariners of the Northwest League. He made 13 starts for the ballclub, accumulating a 6–4 record, a 2.68 ERA, 55 strikeouts, 44 walks, and 85 hits allowed in 84 innings pitched. He joined the Bakersfield Mariners of the Single-A California League in 1982, making 26 starts and posting a 7–11 record, a 4.44 ERA, 82 strikeouts, 69 walks, and 172 hits allowed in 154 innings pitched. With Bakersfield again for the 1983 season, he made 25 starts and had a 12–6 record, a 3.22 ERA, 93 strikeouts, 45 walks, and 164 hits allowed in innings. Guetterman spent most of the 1984 season with the Double-A Chattanooga Lookouts of the Southern League, making 24 starts and posting an 11–7 record, a 3.38 ERA, 47 strikeouts, 38 walks, and 174 hits allowed in 157 innings. At the end of the year, Seattle promoted him to the major leagues as one of their September call-ups. He made his major league debut as a relief pitcher on September 12, allowing one run in innings pitched in an 8–1 loss to the Texas Rangers. Guetterman would make three appearances for Seattle in 1984, allowing two runs in innings. In 1985, Guetterman pitched for the Triple-A Calgary Cannons of the Pacific Coast League (PCL). He appeared in 20 games (18 starts), posting a 5–8 record, a 5.79 ERA, 48 strikeouts, 44 walks, and 138 hits allowed in innings. First full season, use as a starter (1986–87) In 1986, Guetterman made the Mariners' roster out of spring training and spent most of the season as a relief pitcher with the major league club,