3. Dave Krieg
Boy, the Seahawks sure love themselves an undrafted quarteback. Dave Krieg went undrafted back in 1980 coming out of Milton. He was signed as the third string quarterback that year and, by the next season, had earned the backup spot.
By the time the 1982 season rolled around, Krieg had earned the starting quarterback job in that shortened season (strike). However, he played just two games before getting sidelined with a thumb injury.
In 1983, Krieg was relegated to the backup role as Zorn continued to start. But, Zorn would ultimately lose the job with Krieg reclaiming his starting gig. Krieg would go 5-3 as a starter the rest of that year and lead the league with a ridiculous touchdown percentage of 7.4.
The following season, Krieg earned Pro Bowl honors as he went 12-4 as a starter, throwing for 3,671 yards, 32 touchdowns and 24 picks. We won't talk about the fact that those interceptions also led the league.
Overall, Krieg played 12 years in Seattle and became a Seahawks legend. On the Seahawks' all-time passing list, Krieg sits third with 26,132 yards, 195 touchdowns and 132 interceptions. He went 70-49 as a starter.